If you’re on the hunt for a dinner that’s as comforting and satisfying as it is healthy, you’ll want to make room at your table for this Cheesy Vegetarian Spaghetti Squash Casserole. This cozy, crowd-pleasing bake transforms humble spaghetti squash into the ultimate vegetarian centerpiece, layered with a tumble of tender vegetables, bright tomato sauce, and a golden, bubbling lid of cheese. It’s easy enough for weeknights, yet so luscious and cheerful that it honestly feels special every time you serve it up.
Ingredients You’ll Need
The magic of Cheesy Vegetarian Spaghetti Squash Casserole is how it turns just a handful of simple, everyday ingredients into something truly crave-worthy. Every component has a role to play, from adding mouthwatering flavor to giving the casserole its signature melt and stretch.
- Spaghetti squash: Roasted until tender, its noodle-like strands are a wholesome and fun base for all the cheesy goodness.
- Olive oil: For sautéing veggies and adding a subtle richness to the finished dish.
- Yellow onion: Brings gentle sweetness and aromatic depth to the casserole.
- Garlic: Just a couple cloves infuse the whole dish with a punch of garlicky flavor.
- Red bell pepper: Chopped bell pepper offers a pop of sweetness and vibrant color.
- Zucchini: Diced zucchini melts into the sauce, adding bulk and a tender bite.
- Dried oregano: A classic Italian herb that ties the flavors together beautifully.
- Crushed red pepper flakes (optional): For those who like a gentle kick of heat.
- Salt and black pepper: Balances and lifts every bite.
- Canned diced tomatoes: Drained for perfect sauciness and tons of tomato flavor.
- Marinara sauce: Binds everything together with a tangy, herby richness—use your favorite!
- Shredded mozzarella cheese: The star of the “cheesy” show, lending a perfect melt and pull.
- Grated Parmesan cheese: Adds sharp, salty depth and a gorgeous crust on top.
- Fresh basil or parsley: A sprinkle at the end for freshness and vibrant color.
How to Make Cheesy Vegetarian Spaghetti Squash Casserole
Step 1: Roast the Spaghetti Squash
Start by preheating your oven to 400°F (200°C). Carefully slice the spaghetti squash in half lengthwise (a sharp knife and a steady hand help!), then scoop out the seeds. Place the squash halves cut-side down on a baking sheet and roast for 35 to 40 minutes, until the flesh is fork-tender and can be easily shredded into strands. Roasting brings out the natural sweetness and gives you those iconic squash “noodles” that make this dish so fun.
Step 2: Sauté the Veggies
While the squash bakes, grab a large skillet and warm the olive oil over medium heat. Toss in the diced onion and cook until it’s just softened and lightly golden—about 3–4 minutes. Add the garlic, bell pepper, and zucchini, and continue cooking for 5 minutes more. The veggies will get tender and delicious, setting the stage for all that flavor.
Step 3: Build the Sauce
Sprinkle in the dried oregano, crushed red pepper flakes (if you’re using), salt, and black pepper. Stir everything together so the spices coat the vegetables. Next, pour in the drained diced tomatoes and marinara sauce, letting it all simmer for 5 minutes. This step melds all the flavors together and gives the casserole its bright and rich tomato base.
Step 4: Combine with the Squash and Cheese
Once the spaghetti squash has cooled enough to handle, use a fork to gently pull the strands from the skin, creating your “spaghetti.” Fold the squash strands into the skillet with the saucy vegetables and mix until perfectly combined. Stir in 1 cup of the mozzarella cheese—this will start to melt and bind everything together, making the casserole creamy and luscious.
Step 5: Assemble and Bake
Lightly grease a 9×13-inch baking dish and transfer the cheesy veggie mixture into it, spreading evenly. Sprinkle the remaining 1/2 cup of mozzarella and all of the grated Parmesan over the top for a cheesy lid. Pop the dish into your oven and bake for 20 minutes, until the cheese is golden and bubbly. When it comes out, crown with fresh basil or parsley, and soak in the applause at the table.
How to Serve Cheesy Vegetarian Spaghetti Squash Casserole
Garnishes
Nothing completes Cheesy Vegetarian Spaghetti Squash Casserole like a flourish of fresh herbs. Scatter chopped basil or parsley right before serving. It adds a burst of color and a fresh fragrance that lifts all the rich, savory flavors. For an extra-special touch, a sprinkle of extra Parmesan is always welcome, and a quick crack of black pepper looks beautiful, too.
Side Dishes
This casserole can shine as a main course, but it also plays nicely with others. Serve it alongside a crisp green salad tossed with lemon vinaigrette, or add roasted broccoli or garlicky sautéed greens for a pop of color and contrast. Crusty bread is fantastic for sopping up cheesy, tomato-y bits from the dish.
Creative Ways to Present
If you’re feeling a little fancy, portion the hot casserole into individual ramekins for an adorable dinner party presentation. For family-style meals, just scoop straight from the baking dish at the table (the gooey cheese strands are part of the fun). Or, serve it “squash bowl” style: bake the mixture right back in the squash shells for a playful, eco-friendly twist!
Make Ahead and Storage
Storing Leftovers
Leftovers of Cheesy Vegetarian Spaghetti Squash Casserole keep beautifully! Let the casserole cool completely before transferring slices to airtight containers. Store them in the refrigerator for up to 4 days, and enjoy quick, delicious lunches or busy weeknight dinners.
Freezing
To freeze, cut cooled casserole into slices and wrap them individually, or keep the whole dish wrapped tightly with foil. Frozen portions can last up to 2 months. When you’re ready to enjoy, thaw overnight in the fridge for best results.
Reheating
You have a couple of options: reheat slices in the microwave until warmed through, or cover and bake in a 350°F oven until hot and bubbly. Add an extra sprinkle of cheese before reheating for extra yum factor—it will melt right back into the dish.
FAQs
Can I add protein to this Cheesy Vegetarian Spaghetti Squash Casserole?
Yes, absolutely! If you’d like a bit more protein, stir in a can of drained chickpeas or white beans when you combine the squash with the veggies. They’ll pick up all the saucy, cheesy flavors and keep the casserole satisfying.
What’s the best way to cut spaghetti squash safely?
Spaghetti squash can be tough! Use a large, sharp chef’s knife and slice off a thin piece from each end for stability. Stand the squash upright and carefully cut down the center. If you find it extra tricky, microwaving the whole squash for 3–4 minutes can soften it just enough.
Can Cheesy Vegetarian Spaghetti Squash Casserole be made vegan?
Yes! Swap the mozzarella and Parmesan for your favorite dairy-free cheeses. Double-check the marinara sauce is vegan, and you’ll have a delicious, plant-based casserole the whole family can enjoy.
Do I have to roast the squash, or can I microwave it?
While roasting adds beautiful flavor, you can speed things up by microwaving the squash. Pierce the skin several times, microwave on high for 10–12 minutes, then cut, seed, and shred the flesh as directed.
Can I prepare this Cheesy Vegetarian Spaghetti Squash Casserole ahead of time?
Definitely. Assemble the casserole completely, then cover and refrigerate for up to a day before baking. When you’re ready to serve, bake as directed—add a few extra minutes if it’s coming straight from the fridge.
Final Thoughts
I can’t wait for you to dig into the melty, colorful comfort of this Cheesy Vegetarian Spaghetti Squash Casserole! Whether you’re a seasoned vegetarian or just exploring meatless meals, this recipe is sure to become a new favorite. Give it a try, and make it your own with a few simple tweaks—I promise it’ll bring so much joy (and cheese!) to your table.
Print
Cheesy Vegetarian Spaghetti Squash Casserole Recipe
- Prep Time: 15 minutes
- Cook Time: 60 minutes
- Total Time: 1 hour 15 minutes
- Yield: 6 servings
- Category: Main Course
- Method: Baking
- Cuisine: American
- Diet: Vegetarian
Description
Indulge in this delicious Cheesy Vegetarian Spaghetti Squash Casserole, a healthy and satisfying dish that’s bursting with flavor. With a mix of wholesome veggies and gooey cheese, this casserole is a comforting treat for any meal.
Ingredients
For the Spaghetti Squash:
- 1 medium spaghetti squash (about 3 pounds)
- 1 tablespoon olive oil
For the Vegetable Mixture:
- 1 small yellow onion (diced)
- 2 cloves garlic (minced)
- 1 red bell pepper (diced)
- 1 zucchini (diced)
- 1 teaspoon dried oregano
- 1/2 teaspoon crushed red pepper flakes (optional)
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 1 (14.5-ounce) can diced tomatoes (drained)
- 1 cup marinara sauce
For the Cheese Topping:
- 1 1/2 cups shredded mozzarella cheese (divided)
- 1/4 cup grated Parmesan cheese
- 2 tablespoons chopped fresh basil or parsley (for garnish)
Instructions
- Preheat the oven: Preheat the oven to 400°F (200°C).
- Prepare the squash: Slice the spaghetti squash in half lengthwise, remove the seeds, and roast for 35–40 minutes until tender.
- Sauté the veggies: In a skillet, cook onion, garlic, bell pepper, and zucchini. Season with oregano, red pepper flakes, salt, and pepper.
- Combine ingredients: Add diced tomatoes, marinara sauce, and shredded squash to the skillet. Mix in 1 cup of mozzarella.
- Bake: Transfer the mixture to a baking dish, top with remaining cheese, and bake for 20 minutes until bubbly.
- Serve: Garnish with basil or parsley before serving.
Notes
- You can add canned chickpeas or white beans for extra protein.
- Use a marinara sauce with no added sugar for a healthier option.
Nutrition
- Serving Size: 1 slice
- Calories: 210
- Sugar: 6g
- Sodium: 540mg
- Fat: 11g
- Saturated Fat: 5g
- Unsaturated Fat: 5g
- Trans Fat: 0g
- Carbohydrates: 20g
- Fiber: 4g
- Protein: 10g
- Cholesterol: 20mg
