Comfort food that feels like Sunday dinner: creamy, cheesy, and topped with crunchy fried onions. This Monterey Spaghetti combines tender spaghetti with a trio of cheeses, sour cream, ricotta, spinach, and a crisp onion finish. It’s the kind of pasta casserole that travels well to potlucks, feeds a crowd, and comforts on a chilly evening.

Why you’ll love this recipe

Simple, pantry-friendly ingredients.
Rich, creamy sauce without needing a roux.
Spinach adds color and a gentle lift to the richness.
Crispy fried onions give a salty, crunchy contrast that keeps every bite interesting.

Ingredients

8 ounces spaghetti
2 cups Monterey Jack cheese, shredded
1 cup parmesan cheese, shredded and divided
1 cup sour cream
½ cup ricotta cheese
1 large egg
1 teaspoon salt
½ teaspoon pepper
1 teaspoon garlic powder
10 ounces frozen chopped spinach, thawed and drained
6 ounces crispy fried onions, divided

Make-ahead and substitutions

You can cook the spaghetti a day ahead and refrigerate it to speed up assembly. If you prefer a lighter texture, use part-skim ricotta. For a sharper cheese profile, swap half the Monterey Jack for a mild cheddar, keeping amounts the same.

Step-by-step instructions

Preheat oven to 350°F (175°C) and lightly grease a 9×9-inch baking dish or similar-sized casserole dish.
Bring a large pot of salted water to a boil. Add 8 ounces spaghetti and cook until just al dente according to package directions. Drain well and transfer the pasta to a large mixing bowl.
While the pasta cooks, squeeze excess moisture from the thawed 10 ounces frozen chopped spinach using a clean kitchen towel or paper towels. You want the spinach as dry as possible so the casserole won’t be watery.
In a medium bowl, combine 2 cups shredded Monterey Jack cheese, 1 cup shredded parmesan cheese (reserve about ¼ cup of the parmesan for the topping), 1 cup sour cream, ½ cup ricotta cheese, 1 large egg, 1 teaspoon salt, ½ teaspoon pepper, and 1 teaspoon garlic powder. Mix until smooth and evenly combined.
Add the well-drained spinach to the cheese mixture and stir until the spinach is evenly distributed through the sauce.
Pour the spinach-cheese mixture over the cooked spaghetti in the large mixing bowl. Toss gently but thoroughly so the pasta is evenly coated with the creamy mixture.
Transfer the coated spaghetti to the prepared baking dish and spread it into an even layer.
Sprinkle the reserved ¼ cup parmesan cheese evenly over the top, then scatter half of the 6 ounces crispy fried onions across the surface.
Bake in the preheated oven for 20–25 minutes, until the casserole is heated through and the top is bubbly and lightly golden.
Remove the casserole from the oven and immediately sprinkle the remaining crispy fried onions across the top so they stay crunchy.
Let the dish rest for 5 minutes to set slightly, then serve warm. Leftovers store well in the refrigerator for up to 3 days; reheat covered in a 350°F (175°C) oven until warmed through.

Serving ideas

Serve this Monterey Spaghetti with a crisp green salad and a bright vinaigrette to cut through the richness. A side of roasted vegetables or steamed green beans work well, too. If you’re bringing it to a gathering, keep the extra fried onions in a separate container and add them just before serving so they stay crunchy.

Tips for success

Drain the spinach and pasta thoroughly. Excess water is the most common reason casseroles turn out soupy.
Shred your own Monterey Jack and parmesan from blocks for better melting and flavor.
For an extra creamy texture, fold the ricotta into the sour cream first to remove lumps before combining with the other ingredients.
Don’t overbake. Once the casserole is bubbly and lightly golden, it’s done — overbaking will dry it out.

Notes on ingredients

All cheeses should be from good-quality sources and stored properly. If you prefer a stronger nutty finish, use a full cup of freshly grated parmesan and reduce the Monterey Jack by ¼ cup, keeping total cheese amounts the same.

Nutrition estimate (per serving, serves 4)

Approximate values: 540 calories, 28 g fat, 40 g carbohydrates, 26 g protein. These values will vary with specific brands and serving sizes.

Final thoughts

This Monterey Spaghetti is a cozy, straightforward dish that hits comforting-cheesy notes while sneaking in a modest serving of greens. It’s forgiving, adaptable, and reliably satisfying — the kind of recipe you’ll want in your weeknight and potluck rotation.

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Monterey Spaghetti

Creamy baked spaghetti with Monterey Jack, Parmesan, ricotta, spinach, and crispy fried onions.

Prep Time20

Cook Time40

Total Time1

Servings: 8 people

Ingredients

8 ounces spaghetti broken in half
2 cups Monterey Jack cheese shredded
1 cup Parmesan cheese shredded and divided
1 cup sour cream
1/2 cup ricotta cheese
1 large egg
1 teaspoon salt
1/2 teaspoon black pepper
1 teaspoon garlic powder
10 ounces frozen chopped spinach thawed and drained
6 ounces crispy fried onions divided (use about 3 oz in the mixture and remaining for topping)

Instructions

Preheat the oven to 350°F (175°C) and spray a 9x13-inch baking dish with cooking spray.
Break the spaghetti in half and cook in a large pot of boiling salted water according to package directions until al dente; drain well.
In a large bowl, whisk together Monterey Jack, 1/2 cup of the Parmesan, sour cream, ricotta, egg, salt, pepper, and garlic powder until smooth.
Add the drained chopped spinach, about 3 ounces of the crispy fried onions, and the cooked spaghetti to the cheese mixture; toss until evenly combined.
Transfer the mixture to the prepared baking dish, cover tightly with foil, and bake for 30 minutes.
Remove foil, sprinkle the remaining crispy fried onions and the remaining Parmesan over the top, then return to the oven and bake 5–8 minutes more until the top is golden and crispy.
Let the casserole rest at least 5 minutes before serving.