I learned this recipe as a weeknight project that turned into a backyard party favorite. It’s built around a simple strategy: use a reliable cake mix for structure, then add a creamy coconut-sour cream filling that soaks into the layers overnight. The result is a moist, tender cake with a bright coconut personality and a light, cool frosting that holds up in warm weather.

There’s no complicated tempering, no custard to babysit. The long step is mostly passive—letting sugar, sour cream, and sweetened coconut sit together overnight so the coconut softens and the sugar completely dissolves into the cream. The next day you bake, stack, fold in Cool Whip, and chill. It’s forgiving, and once you get the timing down it becomes a go-to for potlucks and birthdays.

I’ll walk you through the essentials, give practical tips for handling layers and frosting, and cover the little fixes that turn good into great. Read everything once, prep the night before, and you’ll be rewarded with a perfectly composed Coconut Cake with Sour Cream Frosting.

The Essentials

Time: Active work is minimal—about 30–45 minutes the day you bake. The important part is the overnight step: combine sugar, sour cream, and sweetened coconut and chill. That gives you a soft, spreadable filling and helps the coconut release flavor into the cream. Bake day is straightforward: make the boxed cake mix, split layers, assemble, and frost.

Equipment-wise, two 8- or 9-inch round pans are ideal for even layers. A serrated knife or cake leveler will make splitting rounds into layers easier. Chill the sour cream mixture overnight and keep the finished cake refrigerated—this recipe uses Cool Whip, so cold storage is necessary.

Planning tip: Start the coconut–sour cream mix the night before you want to serve. Bake and assemble the next day, then let the cake rest in the fridge for at least a couple of hours so the flavors meld and the frosting firms up.

Ingredients

1 box Golden Butter Cake Mix — plus ingredients to make cake as directed on the box; this is the cake’s structure and shortcut for consistent results.
2 cups sugar — macerates with the sour cream to sweeten and soften the coconut; do not reduce without adjusting texture.
1 (16-oz) container sour cream — provides tang, moisture, and body for the coconut mixture; it’s the base of the filling.
1 (14-oz) bag sweetened coconut — gives texture and coconut flavor throughout the layers; the overnight soak softens it for spreading.
1 (12-oz) container Cool Whip, thawed — light whipped topping for the frosting; it keeps the finish airy and refrigerator-stable.

Stepwise Method: Coconut Cake with Sour Cream Frosting

The night before baking, in a medium bowl stir together 2 cups sugar, the entire 16‑oz container sour cream, and the entire 14‑oz bag sweetened coconut until combined. Cover and refrigerate overnight.
The next day, prepare the 1 box Golden Butter Cake Mix according to the package directions for two 8‑ or 9‑inch round cake pans (use the ingredients and amounts called for on the cake mix box). Bake as directed.
Remove the baked cakes from the pans and cool completely on a wire rack. Once cool, level any domes if desired and carefully split each round horizontally into two layers so you have a total of four cake layers.
Remove the sour cream–coconut mixture from the refrigerator and stir it to recombine. Scoop out 1 cup of this mixture and transfer it to a small bowl; set that bowl aside (this will be used for the frosting).
Place one cake layer on your serving plate. Spread an even portion of the remaining sour cream–coconut mixture on top of that layer. Repeat with the next two layers, spreading the remaining mixture evenly between the three inner seams so all four layers are stacked.
In a medium bowl, fold the reserved 1 cup of sour cream–coconut mixture into the thawed 12‑oz container Cool Whip until smooth and evenly combined.
Use the Cool Whip mixture to frost the top and sides of the assembled cake.
Place the finished cake in an airtight container or cover and store in the refrigerator until ready to serve.

Why It Works Every Time

There are two dependable pieces of the formula: the boxed cake mix and the overnight coconut–sour cream soak. The cake mix gives a consistent crumb and rise because the manufacturer has already balanced leavening and fat. Relying on that avoids problems that can come from mismeasured ingredients when you’re in a hurry.

The overnight soak is equally important. Sugar draws moisture out of the sour cream and into the coconut, softening those strands so they’re spreadable and flavorful instead of dry and chewy. That softened coconut becomes a moist, slightly sweet filling between layers. Folding a reserved portion into Cool Whip gives you a light frosting that still tastes of coconut and tang without being heavy or cloying.

Refrigeration keeps the Cool Whip stable and prevents weeping. Because the filling already has moisture, a short chill once assembled helps the crumb absorb some of that cream, making each slice cohesive instead of falling apart.

Flavor-Forward Alternatives

If you want to nudge this cake in a different direction without changing technique, try one of these straightforward swaps or additions:

Top with toasted coconut: Sprinkle the toasted flakes on the top and sides after frosting for crunch and deeper coconut flavor.
Add citrus: A teaspoon of lime or orange zest in the reserved cup folded into Cool Whip brightens the frosting and balances sweetness.
Use a different boxed cake: Vanilla, white, or yellow mixes will all work; a coconut or white cake mix will boost coconut notes.
Garnish with fruit: Fresh berries or thinly sliced mango on the top add color and a fresh counterpoint to the creamy layers.

Tools of the Trade

These are the basics that make the assembly smooth:

Two 8- or 9-inch round cake pans — for even, stackable layers.
Wire cooling rack — for quick, even cooling after baking.
Serrated knife or cake leveler — to split each round into two layers cleanly.
Offset spatula or rubber spatula — for spreading filling and frosting evenly.
Mixing bowls — one medium for the overnight mixture and one for folding frosting.
Airtight container or plastic wrap — to store the finished cake in the refrigerator.

Things That Go Wrong

Here are the common missteps and how to avoid them.

Gummy or runny filling: If the overnight mixture is watery, it might be over-stirred before chilling or the sour cream used was runnier than typical. Stir gently to recombine and reserve the 1 cup as instructed; the Cool Whip will help stabilize the frosting.
Layers sliding or collapsing: Make sure cakes are completely cool before splitting and stacking. Warm cakes will compress and move. Level domes cleanly so each layer sits flat.
Weeping frosting: Keep the cake refrigerated. Warm room temps cause Cool Whip to weep. Serve within a few hours of removing from the fridge once plated.
Overly sweet or cloying result: Use the amount of sugar in the recipe; the balance between tangy sour cream and sweet coconut is intentional. If you prefer less sweetness in future batches, consider swapping sweetened coconut for a mix of unsweetened plus a little sugar—but test before serving to a crowd.

Tailor It to Your Diet

Small swaps can make this more diet-friendly without changing the workflow.

Dairy-free: Use a dairy-free sour cream alternative and a non-dairy whipped topping labeled as stable for refrigeration. Be mindful that textures may vary; do a small test to ensure the coconut softens similarly overnight.
Lower sugar: This recipe relies on 2 cups of sugar for the coconut soak. If you reduce sugar, the coconut will be less sweet and the texture may change. Try reducing gradually and taste the mixture after it chills overnight to adjust expectations.
Egg-free/Allergen-aware: The boxed cake mix contains instructions for eggs; if you need an egg-free cake, choose a box mix labeled egg-free and follow its directions.

Notes from the Test Kitchen

We tested this across a few cake pans and cake-mix brands. Two important takeaways: the Golden Butter cake mix gives a slightly richer background flavor that complements coconut, and splitting each baked round into two thin layers yields the best proportion of cake to filling. Four thin layers absorb the coconut mixture more evenly than two thick ones.

When cooling, allow at least an hour for the cake to reach room temperature on a wire rack before attempting to split. If the cake is even slightly warm, the crumb will tear when you slice horizontally. For cleaner layers, chill the rounds briefly—20–30 minutes in the fridge—so they firm up before cutting.

We also found that reserving exactly 1 cup of the coconut–sour cream mix matters. Too little reserved mix makes the frosting weak on coconut flavor; too much thins the filling in between layers.

Save It for Later

Storage: Keep the cake covered and refrigerated. It will stay fresh for 3–4 days; the coconut filling keeps it moist but also needs cold storage because of the sour cream and Cool Whip.

Freezing: You can freeze slices wrapped tightly in plastic and then foil for up to one month. Thaw overnight in the refrigerator to preserve texture. Whole assembled cakes can be frozen but will have a softer crumb on thawing and the frosting may weep more than when refrigerated only.

Troubleshooting Q&A

Q: My coconut mixture looks dry—what went wrong?
A: If the coconut seems dry after mixing, it may not have sat long enough to soften. Ensure you covered and refrigerated it overnight. If short on time, give it at least a few hours and stir occasionally to encourage moisture distribution, but overnight is best.

Q: The frosting looks uneven and a little loose.
A: Make sure the reserved 1 cup of coconut–sour cream mixture was well combined before folding into the thawed Cool Whip. Fold gently to avoid deflating the topping, and refrigerate the cake so the frosting firms. If it’s still loose, a brief chill before final smoothing can help.

Q: My cake layers are crumbly when I split them.
A: You may be cutting too soon. Cakes should be completely cool. Use a serrated knife with a gentle sawing motion or a cake leveler. Chilling the rounds briefly makes slicing easier and reduces crumbs.

Save & Share

If you make this, photograph a cross-section of the layers—the visual of thin cake, coconut filling, and fluffy coconut frosting tells the story. Share the recipe with someone who enjoys simple techniques that produce impressive results. This Coconut Cake with Sour Cream Frosting is reliably crowd-pleasing and scales well for larger gatherings if you double the box mixes and pans.

Plan: mix the coconut and sour cream the night before, bake and assemble the next day, chill, slice, and enjoy. Practical, forgiving, and very coconut-forward—exactly the sort of recipe I keep returning to.

Print Recipe Save it for later

Coconut Cake with Sour Cream Frosting

A layered golden butter cake filled with a sour cream and sweetened coconut mixture, then frosted with a Cool Whip and reserved sour cream-coconut mixture.

Prep Time15

Cook Time20

Total Time35

Course: Dessert

Servings: 12 servings

Ingredients

1 box Golden Butter Cake Mix ,plus ingredients to make cake
2 cupssugar
1 16-ozcontainer sour cream
1 14-ozbag sweetened coconut
1 12-ozcontainer Cool Whip, ,thawed

Instructions

The night before baking, in a medium bowl stir together 2 cups sugar, the entire 16‑oz container sour cream, and the entire 14‑oz bag sweetened coconut until combined. Cover and refrigerate overnight.
The next day, prepare the 1 box Golden Butter Cake Mix according to the package directions for two 8‑ or 9‑inch round cake pans (use the ingredients and amounts called for on the cake mix box). Bake as directed.
Remove the baked cakes from the pans and cool completely on a wire rack. Once cool, level any domes if desired and carefully split each round horizontally into two layers so you have a total of four cake layers.
Remove the sour cream–coconut mixture from the refrigerator and stir it to recombine. Scoop out 1 cup of this mixture and transfer it to a small bowl; set that bowl aside (this will be used for the frosting).
Place one cake layer on your serving plate. Spread an even portion of the remaining sour cream–coconut mixture on top of that layer. Repeat with the next two layers, spreading the remaining mixture evenly between the three inner seams so all four layers are stacked.
In a medium bowl, fold the reserved 1 cup of sour cream–coconut mixture into the thawed 12‑oz container Cool Whip until smooth and evenly combined.
Use the Cool Whip mixture to frost the top and sides of the assembled cake.
Place the finished cake in an airtight container or cover and store in the refrigerator until ready to serve.