Vegetarian Baked Spaghetti

Combine spaghetti, pasta sauce, and veggies for an easy and sliceable meatless meal! Vegetarian baked spaghetti is great for family dinners and meal prep and is easy to customize.

Recipe features

• Inspired by spaghetti pie because it is sliceable and cooked in a cast-iron skillet. Spaghetti pie usually uses ricotta-coated noodles as a "crust" topped with sauce. This lighter version uses a delicious yet simple combination of spaghetti and tomato sauce baked in a cast-iron dish.
• Family-friendly: Vegetarian baked spaghetti is great for family dinners because it is simple but satisfying.
• Hidden veggies: This recipe features finely diced mushrooms, but you can blend extra veggies into the sauce or omit the mushrooms.
• Great for meatless Mondays and for those who are new to eating meatless meals.

If you like this recipe then you'll love my vegetarian one-pot spaghetti and veggie-packed pasta bake.

Ingredients and substitutions

One of the reasons that I love this recipe is that it is really easy to customize and substitute using whatever you have on hand. 

Here's what you need to make vegetarian baked spaghetti, along with a few ideas for customization:

• Spaghetti noodles: White, whole wheat, or even protein pasta will work. Cook the noodles until al dente so that the baked spaghetti retains texture.
• Pasta sauce: I personally think that homemade pasta sauce is the best part of spaghetti pie, but using a 24-28 ounce jar of store-bought pasta sauce is an easy way to cut down on cooking time.
• Veggies: Finely diced mushrooms add flavor and nutrition. You can also add finely chopped celery, broccoli, carrots, whatever! Just make sure to saute until most of the water is evaporated out and pour off any excess liquid before adding the tomatoes. Make the veggies “hidden” by blending them into the tomato sauce in a blender.
• Mozzarella: Shredded mozzarella acts as “glue” to hold the spaghetti together and is a necessary addition to most casseroles. Make this dish vegan by using an equal amount of vegan shreds instead.
• Protein: If you'd like to add extra plant-based protein, consider sauteing tempeh or plant-based sausages along with the mushrooms.

Step by step instructions

1. Heat a large 12-inch skillet over medium-high heat. Add one tablespoon of olive oil. Once hot, add minced garlic, onions, and finely chopped mushrooms. Sprinkle with ¼ teaspoon salt. Saute 6-8 minutes, or until mushrooms are soft. Drain off excess liquid.
2. Add chopped parsley, rosemary, thyme, and oregano. Saute another 30 seconds to bloom the herbs. Add extra oil as needed. Add the crushed tomatoes with juices, sugar, and black pepper. Simmer for about 15 minutes to allow the flavors to develop. At this point, you can blend the sauce in a blender or move to hte next step.
3. Mix together half of the shredded mozzarella, all of the cooked spaghetti, and all of the pasta sauce. Place in a 12-inch cast-iron skillet or baking dish.
4. Sprinkle with remaining shredded mozzarella. Bake at 350F until the cheese is melted and golden, about 20 minutes.

Expert tips

• Cast-iron: I use a 12 inch cast iron skillet but you can use a regular casserole dish if you don’t have an oven-proof skillet. Any 9x13 or similarly sized heat-proof baking dish will do.
• Moisture: The less watery your veggies are, the better the baked spaghetti holds together. Make sure to salt the mushrooms and onions when you add them to the skillet to draw out extra moisture. Drain off extra moisture before adding tomatoes.
• Cover the spaghetti with as much sauce and cheese as you can to keep it from drying out in the oven.
• Serving ideas: I like to add a green salad like arugula or kale for extra fiber. Serve with a garlic cheddar drop biscuit on the side for the best kind of comfort food meal.

Storage tips

• Leftovers: Keep leftover spaghetti refrigerated in a closed container for 3-4 days.
• Reheating: Reheat individual servings in the microwave or reheat the entire casserole in the oven. To do this, cover with foil and bake at 350F until warmed through, about 15-20 minutes.
• Freezing: Baked spaghetti is great as a freezer meal. It will last in the freezer for up to 3 months. Let the casserole cool to room temp before covering with foil and freezing. You can also slice the casserole and freeze it in individual portions. I like to do this for an easy "freezer dinner". 
• Make-ahead: The pasta sauce can be made up to 48 hours in advance and stored in the fridge. I don't recommend assembling the actual spaghetti casserole in advance because the spaghetti will absorb the sauce and soften as it refrigerates.

More favorite pasta recipes

If you like this recipe you'll love this vegetarian chili mac.

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📖 Recipe

Print Recipe

5 from 2 votes

Vegetarian Spaghetti Pie Casserole

Combine simple ingredients like spaghetti, pasta sauce and veggies for an easy and delicious dinner! Great for meal prep and kid-friendly.

Prep Time25 minutes mins

Cook Time20 minutes mins

Total Time45 minutes mins

Servings: 6 servings

Author: Cassidy Reeser, MS, RD

Ingredients

• ▢ 1 tablespoon extra virgin olive oil
• ▢ 3 cloves garlic minced
• ▢ 8 ounces baby bella mushrooms finely chopped
• ▢ 1 small yellow onion finely chopped
• ▢ ¼ teaspoon salt
• ▢ ¼ cup chopped fresh parsley
• ▢ 1 tablespoon each chopped fresh rosemary, thyme, oregano see note #1
• ▢ 28 ounces crushed tomatoes
• ▢ ½ teaspoon white sugar
• ▢ ⅛ teaspoon black pepper
• ▢ 12 ounces whole wheat spaghetti
• ▢ 1 and ½ cup shredded mozzarella cheese divided

Instructions

• Preheat the oven to 350 degrees F. Lightly butter or oil a 12-inch cast iron skillet or 9x13 casserole dish.
• Heat another large 12-inch skillet over medium-high heat. Add one tablespoon olive oil. Once hot, add minced garlic, finely chopped mushrooms and onion. Add additional veggies here if desired. Sprinkle with ¼ teaspoon salt. Saute 6-8 minutes, or until mushrooms are soft. Drain off excess liquid.
• Add chopped parsley, rosemary, thyme, oregano. Saute another 30 seconds to bloom the herbs. Add extra oil as needed. Add the crushed tomatoes with juices, sugar and black pepper. Bring to a rapid simmer over medium high heat. Reduce to a low simmer over medium-low heat. Simmer for 15 minutes then turn off the heat. Taste for salt.
• Meanwhile, cook the spaghetti to al dente in well salted water according to package instructions. Once cooked, drain the pasta. Transfer spaghetti to the pasta sauce. Stir in ¾ cup shredded mozzarella.
• Transfer spaghetti and sauce mixture to the oiled cast iron pan. Top with remaining ¾ cup of shredded mozzarella.
• Bake at 350F for 20 minutes, or until mozzarella is golden and bubbling. Remove from the oven and let rest 5 minutes before slicing to serve. Enjoy!

Notes

1. Fresh herbs: Rosemary, oregano and thyme can each be replaced with 1 teaspoon dry herbs.
2. Extra veggies: Add carrots, squash or even peas for extra veggies. You can blend the pasta sauce after simmering if you prefer a "hidden veggie" sauce. Be careful if blending as it will be very hot.
3. Store refrigerated in a closed container for up to 5 days. To freeze, cover the cooled casserole with foil and freeze for up to 3 months.

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Serving: 1sliceCalories: 356kcalCarbohydrates: 55gProtein: 18gFat: 10gSaturated Fat: 4gCholesterol: 22mgSodium: 454mgPotassium: 706mgFiber: 3gSugar: 7gVitamin A: 474IUVitamin C: 13mgCalcium: 219mgIron: 4mg