I love a cake that keeps its edges, crackles a little on top, and still manages to be tender in the middle. This Rhubarb Crumb Cake does that, every time. Tart rhubarb folded into a soft, cakey base and finished with a buttery, spiced crumb—it’s exactly the sort of baking I turn to when spring is pressing with fresh produce and a need for something comforting.

There’s nothing fussy here: the crumb is made first while the oven warms, the batter comes together quickly in a mixer, and the rhubarb gets just a little sugar and cornstarch so it behaves in the cake. The final dusting of powdered sugar makes slices look like they belong in a café window, but this is an everyday kind of showoff.

If you keep a stash of cake flour and a small bag of frozen rhubarb, you’ll be surprised how often this one becomes the answer to “what should I bake?” It’s forgiving, honest, and the kind of recipe you’ll make a second time before the first cake is gone.

What’s in the Bowl

Think of this as two parts: a tender, lightly sweet cake batter and a generous, spiced crumb topping. The crumbs get their richness from melted butter and dark brown sugar; the cake is enriched with egg, an egg yolk, and buttermilk so it stays soft even after a long bake. The rhubarb brings the bright, tart contrast that keeps each bite lively.

The recipe balances texture and flavor—soft cake, juicy pockets of rhubarb, and snappy crumbs. It’s straightforward to assemble, and the pan can be lifted out with the parchment for neat slicing once it cools.

Ingredients

⅓ cup (66.67g) granulated sugar — used in the crumb topping to sweeten and help caramelize the crumbs.
⅓ cup (73.33g) dark brown sugar — adds moisture and a deep molasses note to the crumb.
½ teaspoon (0.5 teaspoon) ground cinnamon — warmth for the topping; pairs well with rhubarb.
¼ teaspoon (0.25 teaspoon) ground ginger — bright spice in the crumb topping.
Pinch salt — enhances sweetness and balances flavors in the topping.
8 tablespoons unsalted butter, melted and still warm — binds the topping into a cohesive dough.
1¾ cups (218.75g) cake flour — for the crumb topping structure.
1½ cups (183g) small-diced rhubarb — the cake’s star; provides tart pockets throughout.
2 tablespoons granulated sugar — tossed with the rhubarb to tame sharpness.
1 teaspoon cornstarch — helps thicken released rhubarb juices so the cake doesn’t get soggy.
¼ teaspoon (0.25 teaspoon) ground ginger — a touch of warmth paired with the fruit.
2 teaspoons all-purpose flour — coats the rhubarb to help it disperse through the batter without sinking.
1¼ cups (156.25g) cake flour — the base for the cake batter; keeps the crumb tender.
½ cup (100g) granulated sugar — sweetens the cake batter.
¼ teaspoon (0.25 teaspoon) baking soda — a little lift for the cake’s crumb.
¼ teaspoon (0.25 teaspoon) table salt — balances flavor in the batter.
6 tablespoons unsalted butter, cut into 6 pieces, softened but still cool — cut into the dry mix to create moist crumbs before adding liquids.
1 egg — structure and moisture in the cake.
1 egg yolk — adds richness and tenderness.
1 teaspoon vanilla extract — fragrant background flavor for the batter.
⅓ cup (80ml) buttermilk — acidity for tenderness and a bit of lift.
Powdered sugar, for dusting — optional finish that makes slices look polished.

The Method for Rhubarb Crumb Cake

Make the crumb topping: In a medium bowl whisk the 1/3 cup granulated sugar, 1/3 cup dark brown sugar, 1/2 teaspoon ground cinnamon, 1/4 teaspoon ground ginger, and a pinch of salt into the 8 tablespoons melted (still warm) butter until combined. Add 1 3/4 cups cake flour and stir with a rubber spatula or wooden spoon until the mixture forms a thick, cohesive dough. Set the bowl aside to cool to room temperature, at least 10–15 minutes.
Prep the rhubarb: In a small bowl toss the 1 1/2 cups small-diced rhubarb with the 2 tablespoons granulated sugar, 1 teaspoon cornstarch, and 1/4 teaspoon ground ginger until evenly coated. Set aside.
Preheat and prepare pan: Position a rack in the upper-middle of the oven and preheat to 325°F. Spray an 8-inch square baking dish with nonstick spray and line it with parchment paper, pressing the paper into the corners and allowing excess to overhang the sides.
Combine dry cake ingredients: In the bowl of an electric mixer (or a large bowl if mixing by hand), combine 1 1/4 cups cake flour, 1/2 cup granulated sugar, 1/4 teaspoon baking soda, and 1/4 teaspoon table salt. Mix briefly on low speed just to combine.
Cut in the butter: With the mixer running on low, add the 6 tablespoons softened (but still cool) butter, one piece at a time. Continue beating on low until the mixture resembles moist crumbs with no visible large butter pieces, about 1–2 minutes.
Finish the batter: Add the 1 egg, 1 egg yolk, 1 teaspoon vanilla extract, and 1/3 cup buttermilk to the crumb-like mixture. Increase speed to medium-high and beat until the batter is light and fluffy, about 1 minute, scraping down the bowl once if needed.
Drain and flour the rhubarb: Use a slotted spoon to lift the rhubarb from its bowl so most of the released juice stays behind. Transfer the drained rhubarb to a clean small bowl and toss it with the 2 teaspoons all-purpose flour to coat evenly.
Fold rhubarb into batter: Add the floured rhubarb to the cake batter and gently fold it in with a rubber spatula until evenly distributed, taking care not to overmix.
Assemble cake and add topping: Transfer the batter to the prepared pan and use a rubber spatula to spread it into an even layer. Break the cooled crumb topping into large pea-sized pieces with your fingers or a spoon and scatter them evenly over the batter, starting at the edges and working toward the center.
Bake and cool: Bake until the crumbs are golden and a wooden skewer inserted into the center of the cake comes out clean, 55–65 minutes. Transfer the pan to a wire rack and cool at least 30 minutes.
Finish and serve: Lift the cake from the pan using the parchment overhang, place on a cutting board, and dust with powdered sugar just before slicing and serving.

Reasons to Love Rhubarb Crumb Cake

Bright-tart rhubarb balances a sweet, buttery crumb—every slice tastes lively, not cloying.
The crumb topping offers texture contrast: tender cake beneath and crisp, spiced pieces above.
It keeps well at room temperature and improves in flavor a few hours after baking once the juices settle.
Simple technique: two components come together without complicated tempering or long rests.
Adaptable: swap the fruit or spices and you get a different cake with the same method.

What to Use Instead

If you don’t have fresh rhubarb, frozen chopped rhubarb works; thaw and drain well before tossing with sugar and cornstarch.
Out of cake flour? Use all-purpose flour minus 2 tablespoons per cup (whisk with 2 tablespoons cornstarch per cup) to mimic cake flour’s tenderness.
Buttermilk substitute: 1/3 cup whole milk plus 1 teaspoon lemon juice or vinegar, let sit 5 minutes.
Dark brown sugar swap: use light brown sugar if that’s what you have; you’ll lose a touch of molasses flavor but keep the same texture.
Butter alternatives: salted butter can be used—reduce any added salt in the batter by about 1/8 teaspoon.

What You’ll Need (Gear)

8-inch square baking dish, lined with parchment paper.
Electric mixer with paddle attachment (or a sturdy bowl and wooden spoon if mixing by hand).
Medium and small mixing bowls for topping and rhubarb prep.
Rubber spatula for folding and spreading batter.
Kitchen scale (helpful for accuracy) or dry measuring cups.
Wire rack to cool the cake evenly.
Wooden skewer or toothpick to test doneness.

Frequent Missteps to Avoid

Not cooling the crumb topping before breaking it up—warm crumbs will be gummy and stick to the spatula. Let them cool 10–15 minutes as instructed.
Overmixing when you fold the rhubarb in. Mix just enough to distribute the fruit; overworked batter becomes tough.
Skipping the parchment overhang. Without it, getting neat slices out of the pan is harder and the cake can break.
Adding wet rhubarb to the batter. Drain with a slotted spoon so excess juice stays behind; otherwise the center can become soggy.
Baking at too high a position in the oven. Position the rack upper-middle as directed so the crumbs brown without the top burning.

Seasonal Serving Ideas

Spring: Serve slightly warm with a spoonful of plain yogurt or crème fraîche to echo the rhubarb’s tang.
Summer: Top slices with vanilla ice cream and a drizzle of honey for an easy dessert.
Autumn: Add a scattering of toasted chopped almonds or walnuts to the crumb for nutty warmth.
Holiday mornings: Pair with strong coffee or an herbal tea and a small plate of citrus fruit to brighten the table.

Method to the Madness

Why make the crumb first? The warm, melted butter integrates with the sugars and flour to form a cohesive dough that, once cooled, breaks into pea-sized clumps that bake crisp. If you mixed the topping cold, it would stay powdery and not crisp the same way.

Why flour the drained rhubarb? Coating the fruit in a little flour helps suspend the pieces in the batter so they don’t sink to the bottom during a long bake. The cornstarch you toss with the rhubarb earlier captures excess juice and prevents the cake from becoming a dense, wet mess in the center.

The two-stage fat approach—melted butter for the topping and softened butter cut into the batter—gives different textures. Melted butter creates chew and cohesion for crumbs; small pieces of cold-ish butter mixed into flour make tender, short-like crumbs in the cake before liquid is added. Together they produce a cake that’s both tender and textured.

Prep Ahead & Store

Make Ahead

You can prepare the crumb topping and the rhubarb a day ahead. Store the crumb dough in the refrigerator and let it come to room temperature for 10–15 minutes before breaking it into pieces. Keep the tossed rhubarb in the fridge covered; drain carefully before adding to batter.

Storage

Store leftover cake loosely covered at room temperature for up to 2 days. For longer storage, keep it in an airtight container in the refrigerator for up to 5 days. Rewarm slices in a low oven (300°F) for 8–10 minutes to refresh the crumbs.

Freezing

Freeze sliced cake in a single layer on a baking sheet until firm, then transfer to a freezer bag for up to 2 months. Thaw at room temperature, then warm briefly in the oven if you prefer the crumbs crisp.

Common Questions

Can I use another fruit instead of rhubarb? Yes. Strawberries, raspberries, or a mix of berries work well. Reduce added sugar slightly if you use very sweet fruit.
My crumbs are soggy—what went wrong? Likely the crumb topping was still warm when you attempted to break it up, or the rhubarb released more juice than expected. Let crumbs cool fully and drain rhubarb thoroughly before folding into batter.
Can I halve this recipe? Yes, you can bake it in a smaller pan, but watch baking time closely—the center will set faster in a shallower or smaller pan.
Do I have to use cake flour? Cake flour gives the tender crumb the recipe aims for. You can substitute with a homemade cake-flour substitute (all-purpose flour minus a little, plus cornstarch) if needed.

Hungry for More?

If you liked this Rhubarb Crumb Cake, try a lemon crumb loaf for a brighter, citrus-forward riff, or a simple apple crumb coffee cake when apples come in. For a modern twist, fold a cup of macerated berries into the batter in place of the rhubarb. Bookmark this one—it’s the kind of recipe you’ll reach for whenever a carton of rhubarb arrives on your doorstep or a neighbor hands you a handful with a smile.

Happy baking—slice generous pieces, share with good people, and keep one for yourself.

Print Recipe Save it for later

Rhubarb Crumb Cake

Rhubarb Crumb Cake is a delightful treat that perfectly balances…

Prep Time30

Cook Time1

Total Time1 30

Course: Dessert

Servings: 8 servings

Ingredients

1/3 cup 66.67 ggranulated sugar
1/3 cup 73.33 gdark brown sugar
1/2 teaspoon 0.5 teaspoonground cinnamon
1/4 teaspoon 0.25 teaspoonground ginger
Pinchsalt
8 tablespoonsunsalted butter melted and still warm
1 3/4 cups 218.75 gcake flour
1 1/2 cups 183 gsmall-diced rhubarb
2 tablespoonsgranulated sugar
1 teaspooncornstarch
1/4 teaspoon 0.25 teaspoonground ginger
2 teaspoonsall-purpose flour
1 1/4 cups 156.25 gcake flour
1/2 cup 100 ggranulated sugar
1/4 teaspoon 0.25 teaspoonbaking soda
1/4 teaspoon 0.25 teaspoontable salt
6 tablespoonsunsalted butter cut into 6 pieces, softened but still cool
1 egg
1 egg yolk
1 teaspoonvanilla extract
1/3 cup 80 mlbuttermilk
Powdered sugar for dusting

Instructions

Make the crumb topping: In a medium bowl whisk the 1/3 cup granulated sugar, 1/3 cup dark brown sugar, 1/2 teaspoon ground cinnamon, 1/4 teaspoon ground ginger, and a pinch of salt into the 8 tablespoons melted (still warm) butter until combined. Add 1 3/4 cups cake flour and stir with a rubber spatula or wooden spoon until the mixture forms a thick, cohesive dough. Set the bowl aside to cool to room temperature, at least 10–15 minutes.
Prep the rhubarb: In a small bowl toss the 1 1/2 cups small-diced rhubarb with the 2 tablespoons granulated sugar, 1 teaspoon cornstarch, and 1/4 teaspoon ground ginger until evenly coated. Set aside.
Preheat and prepare pan: Position a rack in the upper-middle of the oven and preheat to 325°F. Spray an 8-inch square baking dish with nonstick spray and line it with parchment paper, pressing the paper into the corners and allowing excess to overhang the sides.
Combine dry cake ingredients: In the bowl of an electric mixer (or a large bowl if mixing by hand), combine 1 1/4 cups cake flour, 1/2 cup granulated sugar, 1/4 teaspoon baking soda, and 1/4 teaspoon table salt. Mix briefly on low speed just to combine.
Cut in the butter: With the mixer running on low, add the 6 tablespoons softened (but still cool) butter, one piece at a time. Continue beating on low until the mixture resembles moist crumbs with no visible large butter pieces, about 1–2 minutes.
Finish the batter: Add the 1 egg, 1 egg yolk, 1 teaspoon vanilla extract, and 1/3 cup buttermilk to the crumb-like mixture. Increase speed to medium-high and beat until the batter is light and fluffy, about 1 minute, scraping down the bowl once if needed.
Drain and flour the rhubarb: Use a slotted spoon to lift the rhubarb from its bowl so most of the released juice stays behind. Transfer the drained rhubarb to a clean small bowl and toss it with the 2 teaspoons all-purpose flour to coat evenly.
Fold rhubarb into batter: Add the floured rhubarb to the cake batter and gently fold it in with a rubber spatula until evenly distributed, taking care not to overmix.
Assemble cake and add topping: Transfer the batter to the prepared pan and use a rubber spatula to spread it into an even layer. Break the cooled crumb topping into large pea-sized pieces with your fingers or a spoon and scatter them evenly over the batter, starting at the edges and working toward the center.
Bake and cool: Bake until the crumbs are golden and a wooden skewer inserted into the center of the cake comes out clean, 55–65 minutes. Transfer the pan to a wire rack and cool at least 30 minutes.
Finish and serve: Lift the cake from the pan using the parchment overhang, place on a cutting board, and dust with powdered sugar just before slicing and serving.