Name: Cheesy Vegetarian Spaghetti Squash Casserole Recipe
Prep time: 20 min
Cook time: 1 h 5 min
Total time: 1 h 25 min
Cuisine: American
Ingredients: 1 medium spaghetti squash (about 3 pounds); 1 tablespoon olive oil; 1 small onion, diced; 2 garlic cloves, minced; 1 zucchini, diced; 1 red bell pepper, diced; 1 teaspoon Italian seasoning; Salt and pepper to taste; 1 cup marinara sauce; 1 ½ cups shredded mozzarella cheese; 1/4 cup grated Parmesan cheese; 2 tablespoons chopped fresh basil or parsley (optional, for garnish)

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If you’re hunting for an irresistible weeknight dinner that blends comfort and freshness, this Cheesy Vegetarian Spaghetti Squash Casserole is about to become your new go-to. Brimming with hearty veggies, melty cheese, and nutrient-rich spaghetti squash, this dish packs all the cozy satisfaction of classic casseroles without any heaviness. It’s naturally gluten-free, easy to prep ahead, and a guaranteed hit whether you’re feeding family or entertaining friends. Each bite delivers a medley of vibrant flavors and textures, making it the perfect meatless main that fills you up and leaves you smiling.

Cheesy Vegetarian Spaghetti Squash Casserole Recipe - Recipe Image

Ingredients You’ll Need

With just a handful of wholesome, everyday ingredients, Cheesy Vegetarian Spaghetti Squash Casserole shines with fabulous flavor and color. Each ingredient brings something essential to the table, from the sweet earthiness of spaghetti squash to the lush richness of the cheese—don’t skip a thing!

Spaghetti squash: Once roasted, its golden strands create a naturally gluten-free, noodle-like base that keeps things light and wholesome.
Olive oil: A touch of olive oil helps soften the veggies and adds a subtle buttery note.
Onion: Diced onion gives a flavorful backbone to the sautéed vegetable mix.
Garlic: Freshly minced garlic adds that must-have, mouthwatering aroma and depth.
Zucchini: Diced zucchini bulks up the veggie content with gentle sweetness and tender bites.
Red bell pepper: Brings sweetness and vibrant color, making every slice pop visually and in flavor.
Italian seasoning: This blend ties all the veggies together with a savory, herbaceous touch.
Salt and pepper: Essential for seasoning everything to perfection—taste and adjust as you go!
Marinara sauce: Adds a tangy tomato base that melds beautifully with the noodles and cheese.
Mozzarella cheese (shredded): The secret to that gooey, irresistible cheesy texture throughout the casserole.
Parmesan cheese (grated): Gives every bite a salty, umami-rich finish and irresistible golden crust.
Fresh basil or parsley (optional, for garnish): Adds a fresh, herbaceous burst just before serving—highly recommended for color and aroma!

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 your spaghetti squash in half lengthwise and scoop out the seeds—you’ll probably want to use a sturdy spoon for this. Place the squash, cut side down, on a baking sheet. Roasting for 35 to 40 minutes will soften the flesh and make it easy to shred into tender, noodle-like strands. Once it’s done, let it cool just enough to handle, then use a fork to transform that squash into beautiful spaghetti-like ribbons.

Step 2: Sauté the Vegetables

While your squash is roasting, warm up a splash of olive oil in a large skillet over medium heat. Toss in your diced onion first and let it soften for about three minutes—this lays down a sweet, savory base. Next, add the garlic, diced zucchini, and bell pepper. Sauté everything together for another five to six minutes until the veggies are tender and aromatic, then season with Italian seasoning, plus plenty of salt and pepper for a full, robust flavor.

Step 3: Combine and Layer

Reduce the oven temperature to 375°F (190°C) for casserole perfection. In a big mixing bowl, add your freshly shredded spaghetti squash, sautéed veggies, marinara sauce, and one cup of mozzarella cheese. Stir until everything is well combined—the colors and scents will already have you anticipating the cheesy vegetarian spaghetti squash casserole’s final reveal! Spoon the mixture into a greased 9×9-inch baking dish, making sure to level the top.

Step 4: Top with Cheese and Bake

Now it’s time for the magic finishing touches: scatter the remaining 1/2 cup of mozzarella over the top, followed by a generous sprinkle of grated Parmesan. Slide the casserole into the oven and bake for 20 to 25 minutes, until it’s bubbling, golden, and gloriously gooey. Let it rest for five minutes before serving—just enough time to gather everyone at the table!

Step 5: Garnish and Serve

If you’re feeling fancy, sprinkle plenty of freshly chopped basil or parsley over the bubbling casserole just before serving. The fresh herbs not only make it look fantastic, but they also layer on a pop of aroma that elevates every bite.

How to Serve Cheesy Vegetarian Spaghetti Squash Casserole

Garnishes

A final flourish of fresh chopped basil or parsley is my favorite way to finish this casserole. The herbs brighten up each serving and add a lovely contrast to the melty cheese. For even more flavor, try a drizzle of good olive oil or a sprinkle of extra grated Parmesan. If you’re a fan of a little kick, offer crushed red pepper flakes or a dash of fresh cracked black pepper right at the table.

Side Dishes

This Cheesy Vegetarian Spaghetti Squash Casserole can be a star on its own, but it also pairs beautifully with a crisp green salad tossed in citrusy vinaigrette or a steaming bowl of minestrone soup. For bigger appetites, accompany it with roasted broccoli or garlic bread for dipping into the sauce—trust me, nobody will complain about seconds!

Creative Ways to Present

Take your presentation to the next level by serving individual portions in mini ramekins or small baking dishes. For a fun family-style twist, bake the casserole directly in the hollowed spaghetti squash shells—it’s impressive, eco-friendly, and gives everyone their own personal bowl. Garnish with basil leaves and a wedge of lemon for a restaurant-worthy plate at home.

Make Ahead and Storage

Storing Leftovers

Got extra Cheesy Vegetarian Spaghetti Squash Casserole? Just let it cool to room temperature, then cover the dish tightly or transfer leftovers to airtight containers. It’ll keep in the fridge for up to four days, tasting just as fabulous for packed lunches or easy reheat-and-eat dinners throughout the week.

Freezing

If you’d like to make this casserole ahead of time, you’re in luck—it freezes beautifully. Assemble the casserole (but don’t bake), cover well with foil, and freeze for up to two months. When you’re ready to enjoy, let it thaw overnight in the fridge for best results, then bake as directed. You can also freeze individual cooked portions for quick, single-serve lunches.

Reheating

To reheat, simply cover the casserole with foil and warm in a 350°F oven until heated through, usually about 20 minutes. For single servings, the microwave works in a pinch—just be sure to use a microwave-safe dish and cover loosely to prevent drying out. A sprinkle of extra cheese before reheating makes each portion taste freshly baked all over again!

FAQs

Can I make Cheesy Vegetarian Spaghetti Squash Casserole vegan?

Absolutely! Substitute your favorite dairy-free mozzarella and Parmesan cheese alternatives to create a completely plant-based, cheesy vegetarian spaghetti squash casserole that still satisfies and melts beautifully.

What’s the best way to cut spaghetti squash safely?

Use a large, sharp chef’s knife and work slowly, carefully slicing off the ends before cutting the squash in half lengthwise. If it’s very tough, try microwaving the whole squash for a minute or two to soften it slightly and make slicing safer.

Can I add more veggies or swap some ingredients?

Definitely! Try adding mushrooms, baby spinach, or sliced black olives for extra flavor and color. This casserole is endlessly adaptable—just be sure not to overload it, so everything bakes up golden and bubbly.

Is this recipe suitable for meal prep?

Yes—it’s perfect for meal prepping because it keeps well in the fridge and reheats easily. Bake a batch on Sunday and enjoy quick, wholesome lunches or dinners all week long.

Can I make Cheesy Vegetarian Spaghetti Squash Casserole ahead of time?

You sure can. Assemble everything right up to the final cheese topping, then cover and refrigerate for up to 24 hours before baking. It’s a huge timesaver for parties or busy weeknights!

Final Thoughts

If you’re craving a hearty, veggie-packed meal that feels as nourishing as it is delicious, don’t miss out on trying Cheesy Vegetarian Spaghetti Squash Casserole. It’s a crowd-pleaser that never disappoints, and once you taste that bubbly, golden cheesy top, you’ll understand why it’s forever on my weeknight dinner rotation. Happy cooking!

Cheesy Vegetarian Spaghetti Squash Casserole Recipe

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4.6 from 18 reviews

Author: admin
Total Time: 1 hour 25 minutes
Yield: 4 servings 1x
Diet: Vegetarian, Gluten-Free

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Description

This Cheesy Vegetarian Spaghetti Squash Casserole is a delightful and flavorful dish that combines roasted spaghetti squash with sautéed vegetables, marinara sauce, and a generous amount of gooey cheese. Perfect for a comforting and satisfying meal.

Ingredients

Scale

For the spaghetti squash:

1 medium spaghetti squash (about 3 pounds)
1 tablespoon olive oil

For the vegetable sauté:

1 small onion, diced
2 garlic cloves, minced
1 zucchini, diced
1 red bell pepper, diced
1 teaspoon Italian seasoning
Salt and pepper to taste

For the casserole:

1 cup marinara sauce
1 ½ cups shredded mozzarella cheese
1/4 cup grated Parmesan cheese
2 tablespoons chopped fresh basil or parsley (optional, for garnish)

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Instructions

Preheat the oven: Preheat the oven to 400°F (200°C). Cut the spaghetti squash in half lengthwise and scoop out the seeds. Roast for 35–40 minutes, or until tender. Shred the flesh into strands.
Sauté the vegetables: In a skillet, cook onion until softened. Add garlic, zucchini, and bell pepper. Sauté until tender. Season with Italian seasoning, salt, and pepper.
Assemble the casserole: Combine spaghetti squash, sautéed vegetables, marinara sauce, and 1 cup mozzarella. Transfer to a baking dish. Top with remaining mozzarella and Parmesan.
Bake: Bake at 375°F (190°C) for 20–25 minutes until bubbly and golden. Let rest before serving. Garnish with herbs.