Spaghetti Squash Casserole Recipe

This Spaghetti Squash Casserole recipe is creamy, cheesy, and packed with comforting flavors for a satisfying keto-friendly side dish.

Pin it to Save it!

Baked until golden and bubbling, it transforms simple ingredients into a nourishing meal perfect for any dinner table.

Inside This Spaghetti Squash Casserole: Key Ingredients

Spaghetti squash – Roasted until tender, it serves as a flavorful, low-carb base with a subtly sweet taste and satisfying texture.

Butter – Melts into the warm squash to add richness and enhance flavor depth.

Sour cream – Contributes to the casserole’s creamy consistency and tangy balance.

Garlic – Minced for aromatic sharpness that complements the mellow squash.

Italian seasoning – A blend of herbs that brings warmth and savory notes.

Cheddar cheese – Adds a robust, sharp creaminess that blends beautifully when melted.

Eggs – Help bind the ingredients into a cohesive, sliceable casserole.

Parmesan cheese – Freshly grated for salty, nutty complexity and a crisp golden topping.

Mozzarella – Melts over the top to create that irresistible gooey, bubbly layer.

Fresh basil – Adds a vibrant, herbaceous finish just before serving.

How to Make This Spaghetti Squash Casserole

First, roast the spaghetti squash until it’s fork-tender, allowing its natural sweetness to shine. Mix the squash with butter, sour cream, and seasonings, then stir in cheeses and eggs for structure.

Once transferred to a casserole dish, it’s topped with more cheese and baked again until golden brown and bubbling—ready to serve with a sprinkle of fresh basil.

Tips for Making the Best Spaghetti Squash Casserole

For optimal flavor, roast the squash until deeply golden and tender—this concentrates its flavor and prevents sogginess. Shredding your own cheese helps avoid anti-caking additives that affect melting. Adjust the red pepper flakes for desired heat, and consider adding crumbled sausage or cooked spinach for variety.

Storing and Reheating Your Spaghetti Squash Casserole

Leftovers keep well in the refrigerator for up to 5 days, tightly wrapped to maintain moisture. To freeze, store portions in airtight containers for up to 2 months. Let thaw in the fridge overnight before reheating in a 350ºF oven until warmed through.

Pin it to Save it!

Frequently Asked Questions

Can I prepare this casserole ahead of time?
Yes, assemble it up to a day in advance and refrigerate. Bake just before serving for the best texture and flavor.

Can I substitute another cheese?
Absolutely. Fontina, Gruyère, or Monterey Jack would all melt well and complement the squash.

How do I make it more filling?
Stir in cooked ground turkey or sausage before baking for a heartier main dish.

Is this recipe gluten-free?
Yes, all ingredients used are naturally gluten-free, making it suitable for those with gluten sensitivities.

Would you like to add a printable recipe card or include nutritional insights per ingredient?

Spaghetti Squash Casserole

Creamy and satisfying, this Spaghetti Squash Casserole serves as an ideal keto-friendly side, delivering rich, cheesy flavor in every bite. It’s a warm and hearty addition to any dinner table.

Print Pin Rate

Prep Time: 20 minutes minutes

Cook Time: 1 hour hour 35 minutes minutes

Total Time: 1 hour hour 55 minutes minutes

Ingredients

• 2 tablespoons butter
• 1 ounce 28.35 g freshly grated Parmesan, divided
• 4 ounces 113.4 g mozzarella, grated
• 1/4 teaspoon red pepper flakes
• 1 medium spaghetti squash approximately 3 pounds
• 4 ounces 113.4 g white cheddar, grated
• 2 large eggs
• 3/4 teaspoon salt
• 2 tablespoons chopped fresh basil
• 1/2 teaspoon black pepper
• 1 teaspoon Italian seasoning
• 4 garlic cloves minced
• 1/2 cup 115 g sour cream

Instructions

• Preheat oven to 375ºF and line a baking sheet with parchment paper.
• Slice the spaghetti squash in half crosswise, remove the seeds, and lay the halves cut-side down on the prepared sheet. Roast for 45 to 60 minutes, or until the flesh yields slightly when squeezed.
• Allow the squash to cool briefly, then scoop the flesh into a large bowl and stir in the butter until melted.
• Lower the oven temperature to 350ºF and lightly grease a 2-quart casserole dish.
• Incorporate the sour cream, minced garlic, Italian seasoning, salt, pepper, and red pepper flakes into the squash mixture. Stir until evenly blended.
• Mix in the eggs, shredded cheddar, and half the Parmesan until fully incorporated.
• Transfer the mixture into the prepared casserole dish and sprinkle the surface with mozzarella and the remaining Parmesan.
• Bake for 30 to 35 minutes, or until the top is bubbling and golden brown.
• Let rest for several minutes before serving. Garnish with extra basil if desired.

Notes

To store, refrigerate for up to 5 days or freeze for up to 2 months. Wrap securely to prevent freezer burn, and bring to room temperature before reheating in the oven.