This 6-ingredient spaghetti squash pizza casserole recipe is vegan and gluten free. Great for a simple weeknight dinner or meal prep.

I realize that a lot (A LOT) of my recipes are either taco related or pizza, but I haven't heard any complaints! I could seriously live off tacos and pizza, they're just so delicious and always hit the spot.

Why you'll love this recipe
- Loaded with veggies: This dish is filled with fresh veggies like mushroom and onion. Feel free to add other vegetables like bell pepper or spinach!
- Quick and easy to make: It's seriously so simple, as the oven does most of the work. It's one of those recipes perfect for busy weeknights that also serve as an awesome lunch the next day.
- Allergy friendly: Just like all of my recipes, this one is dairy free and egg free! Since there's no meat, it's also vegan and vegetarian. As an added bonus, it's also gluten free since the spaghetti squash is acting as the pasta.

Ingredient notes
- Spaghetti squash: Grab a medium to large spaghetti squash at the grocery store.
- Fresh vegetables: Use your favorite pizza toppings like mushrooms, onion, and black olives.
- Marinara sauce: Store-bought or homemade! I prefer using marinara sauce vs pizza sauce since it’s often more thin and has a richer flavor profile.
- Vegan cheese: Use your favorite vegan mozzarella shredded cheese.
- Seasoning: I kept this recipe pretty simple and classic, seasoning with just salt and pepper – but feel free to add some garlic powder, oregano, or even fresh basil to garnish.

How to make spaghetti squash pizza casserole
Start by cooking the spaghetti squash. Here's my guide how to cook spaghetti squash in the oven if you've never done it before. Basically, you’ll first cut the ends off of the squash. Carefully slice the squash in half lengthwise and scrape the seeds out. Drizzle with olive oil and sprinkle with salt and pepper.
Place the halves onto a baking sheet and bake until tender, about 30-45 minutes. Once cooked, remove from oven and let cool slightly. Use a fork to scrape the squash and create long spaghetti-like strands.
In a large skillet, cook down the onion and mushroom, or any other pizza toppings you'll be tossing into your casserole. Add the cooked spaghetti squash, season, then transfer to a large casserole dish that's been sprayed with cooking oil.
Top with vegan shredded cheese and bake at 375F for about 25 minutes, or until cheese has melted. Remove from the oven and let cool slightly before serving. Serve with a big kale salad and dairy free dinner rolls!

Cooking tips
- Don’t overcook the squash, 30-45 minutes is perfect depending on the size of the squash and your oven.
- If your spaghetti squash casserole is a little too watery, place the cooked and shredded squash in a colander to drain the extra liquid.
- Before slicing and serving the baked casserole, let it sit for 5-10 minutes. This will help solidify everything and ensure you don’t burn your mouth!
- Store leftovers in an airtight container in the refrigerator for up to 5 days.

Related recipes
- Vegan broccoli rice casserole comes together with simple ingredients in about 45 minutes. The whole family will love this comfort food classic!
- Vegan penne alla vodka is an easy weeknight meal and will quickly become a family favorite. It's rich, creamy, and satisfying.
- Vegan bolognese features savory crumbled tofu in a rich tomato sauce. It's full of flavor, has a variety of texture, and is easy to make. Perfect for a quick weeknight dinner!
- Vegan mac and cheese without cashews is quick and easy to make. This hidden veggie mac and cheese is ready in 30 minutes, with 3 main ingredients plus spices.

Vegan Spaghetti Squash Pizza Casserole
Equipment
Ingredients
- 1 spaghetti squash medium-large
- 1 small onion chopped
- ½ cup sliced mushrooms
- ¼ cup sliced black olives
- 1 cup marinara sauce
- 1 cup vegan shredded cheese
- 1 teaspoon sea salt
- ½ teaspoon black pepper
Instructions
- Preheat the oven to 400F and line a baking sheet with parchment paper. Cut the ends of the squash and carefully slice in half lengthwise. Scoop out the seeds, drizzle with olive oil, and season with salt and pepper. Arrange cut-side down and bake until tender, 30-45 minutes. Remove from the oven and let cool slightly. Use a fork to scrape the squash and create long spaghetti-like strands.
- Towards the end of the squash baking, cook onion and mushroom in a large pan over low-medium heat. You want the onion to be soft and translucent and the mushroom cooked down a bit.
- Turn off the heat and mix in black olives, spaghetti squash, salt, and pepper. Stir in marinara until well combined.
- Transfer mixture to a 9x13-inch casserole dish, top with vegan shredded cheese, and any additional toppings.
- Reduce the oven temperature to 375F. Bake for 25 minutes or until heated through and cheese has melted. Remove from oven and let cool slightly. Serve and enjoy!
Nutrition

Amanda
I've done something similar with gluten free pasta, but I really love the idea of the spaghetti squash. It is a great way to lighten up the meal. I'm glad to see that it reheats well, too. Perfect for my husband's lunches!
Jenna | The Urben Life
Absolutely 🙂 Let me know if you give it a try!