This vegetarian stuffed spaghetti squash is bursting with lasagna flavor from tomato sauce and ricotta and mozzarella cheeses. Sauteed mushrooms and spinach take the place of meat in this delicious and vegetable-packed main dish.

Two stuffed spaghetti squash halves on a baking sheet with parchment paper

As a Registered Dietitian, I love when vegetables become super popular and more mainstream. Spaghetti squash has skyrocketed in popularity in recent years, because it can be used as a lower carb alternative to pasta. Don’t get me wrong – I LOVE pasta – but there is certainly room for both spaghetti squash and pasta in your diet!

This vegetarian spaghetti squash recipe is a must if you enjoy spaghetti squash. Strands of spaghetti squash are combined with sauteed mushrooms and spinach and tomato sauce, then stuffed back into the spaghetti squash skins and baked. Baked spaghetti squash boats like these are a fun and easy way to prepare this winter squash!

This recipe is vegetarian, gluten free, nut free, and soy free. It serves two people as a main dish.

Ingredients

Here is everything you need to make this stuffed spaghetti squash recipe:

  • Spaghetti squash
  • Mushrooms
  • Baby spinach
  • White onion
  • Garlic
  • Tomato sauce
  • Basil
  • Ricotta cheese
  • Shredded mozzarella cheese
  • Italian seasoning
  • Olive oil
  • Salt
  • Pepper

Kitchen tools needed

You don’t need anything fancy to prepare this meal. I recommend a sharp knife to cut through the spaghetti squash, a large baking sheet, and parchment paper to line the baking sheet for easy clean up.

Ingredients for stuffed spaghetti squash measured out on a grey backdrop

How to cut spaghetti squash

The outer skin on spaghetti squash is quite tough and hard to cut through. To make it much easier to cut, pierce a few holes in the squash using a fork. Then microwave the whole squash for 3-5 minutes. This makes the squash softer and easier to cut through, without cooking it internally.

Best way to cook spaghetti squash

For stuffed spaghetti squash boats, the best way to cook spaghetti squash is cut in half the long way in the oven. Line a baking sheet with parchment paper, and preheat the oven to 400 degrees F.

Prick a few holes in the squash with a fork. Then, microwave the whole squash for 3-5 minutes to soften it up a bit. This makes it easier to cut into.

Use a sharp knife to cut the spaghetti squash into to equal sized halves the long way.

Scoop out the seeds with a spoon and discard them. Drizzle a bit of olive oil on the inside of the squash halves, along with a pinch of salt and pepper.

Place the squash, cut side down, on the parchment paper lined baking sheet. Bake in the oven for about 30 minutes, until you can easily pierce the skin with a fork.

Flip the squash over and use a fork to scoop out the strands of squash when it is cool enough to handle.

Two stuffed spaghetti squash halves on a baking sheet with parchment paper

Step by step instructions

Start by cooking the spaghetti squash in the oven, as outlined above.

While the spaghetti squash is in the oven, prepare the filling. Saute onion and garlic in olive oil, then add sliced mushrooms. Cook until mushrooms are tender and add Italian seasoning and baby spinach.

Use a fork to scoop out the strands of spaghetti squash and transfer to a mixing bowl. Save the two spaghetti squash halves.

Add the sauteed mushrooms and spinach along with tomato sauce and basil. Mix it all together. Add this mixture back to the two spaghetti squash halves.

Top each spaghetti squash boat with more tomato sauce, ricotta cheese, and mozzarella cheese. Bake in the oven until warm and cheese is melted.

Serve warm from the oven with fresh basil sprinkled on top.

Close up of a spaghetti squash boat before it has been baked, topped with ricotta cheese and shredded cheese

Storing stuffed spaghetti squash

If you are cooking for yourself, you can store the other spaghetti squash half in the fridge for a day or two after you make it. Store it upright in an airtight container, or on a plate covered with tin foil.

Reheat it in the oven at 300 degrees F for about 20 minutes, until it is hot and cheese is melted.

Serving suggestions

This recipe is a good vegetarian meal as is, but feel free to add your favorite protein to make it more filling. Since this meal is relatively low in carbohydrates, you can serve it with fresh bread on the side to boost the carb content – this will also make the meal more filling.

Two stuffed spaghetti squash halves on a baking sheet with parchment paper

Spaghetti squash nutrition benefits

Just like all winter squashes, spaghetti squash is a nutritious food to include in your diet. It is a source several micronutrients, including potassium, B vitamins, Vitamin C, Vitamin E, Vitamin K, magnesium, and zinc.

One cup of cooked spaghetti squash provides 2.2 grams of dietary fiber, which is 8 percent of your daily fiber needs. A diet high in fiber has several health benefits, including weight management and promoting heart, digestive, and gut health.

Spinach nutrition benefits

Spinach is loaded with nutrients! One cup of cooked spinach provides:

  • 4.7 grams of dietary fiber (17 percent of your daily needs)
  • 6.1 grams of plant-based protein
  • 209 mg calcium (16 percent of your daily needs)
  • 5.7 mg iron (32 percent of your daily needs)
  • 1179 mg potassium (25 percent of your daily needs)
  • 941.40 mcg Vitamin A (105 percent of your daily needs)
  • 307.8 mcg folate (77 percent of your daily needs)
  • 41.6 mg Vitamin C (46 percent of your daily needs)
  • 1019.5 mcg Vitamin K (850 percent of your daily needs)

In addition, spinach contains several antioxidant compounds that help prevent diseases, keep our cells healthy, and fight inflammation.

Let me know if you love this recipe by leaving a comment or star rating below, and check out Instagram and Pinterest for more healthy lifestyle inspiration. Thanks for stopping by!

Print
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Two stuffed spaghetti squash halves on a baking sheet with parchment paper

Vegetarian Lasagna Stuffed Spaghetti Squash

  • Author: Alex Aldeborgh
  • Prep Time: 45 minutes
  • Cook Time: 15 minutes
  • Total Time: 1 hour
  • Yield: serves 2
  • Category: main dish
  • Cuisine: Italian
  • Diet: Vegetarian

Description

This vegetarian stuffed spaghetti squash is bursting with lasagna flavor from tomato sauce and ricotta and mozzarella cheeses. Sauteed mushrooms and spinach take the place of meat in this delicious and vegetable-packed main dish.


Ingredients

Scale
  • 1 large spaghetti squash
  • 1 tbsp olive oil
  • 1 small white onion, diced
  • 3 cloves garlic, minced
  • 2 1/2 cups sliced baby bella mushrooms
  • Salt
  • Pepper
  • 4 cups baby spinach
  • 1/2 tsp Italian seasoning
  • 1 1/2 cups tomato sauce
  • 1/4 cup fresh basil, chopped
  • 4 oz ricotta cheese
  • 1/2 cup shredded mozzarella cheese

Instructions

  1. Preheat oven to 400 degrees F. Line a baking sheet with parchment paper.
  2. Cut spaghetti squash in half the long way (see notes for tips). Drizzle the cut sides with olive oil and a pinch of salt and pepper.
  3. Place the squash halves, cut side down, on the baking sheet. Bake in the oven for 30-45 minutes, until you can easily pierce the skin with a fork.
  4. Flip the squashes over using oven mitts to let them cool.
  5. Heat olive oil on medium heat in a saute pan. Add onion and garlic, cooking for 1-2 minutes until fragrant.
  6. Add the sliced mushrooms. Cook for another 5-7 minutes, stirring occasionally, until mushrooms are soft.
  7. Add the spinach and Italian seasoning to the mushrooms, then cook until spinach is wilted. Remove from heat.
  8. Use a fork to scrape out the flesh of the spaghetti squash into noodle-like strands. Put these in a mixing bowl, and reserve the outer shells.
  9. To the same mixing bowl, add the mushroom and spinach mixture, 1 cup of tomato sauce, fresh basil, and a pinch of salt. Mix it all up to combine.
  10. Transfer this mixture  back into the two spaghetti squash shells equally. 
  11. Top each shell with an equal amount of the remaining tomato sauce, ricotta cheese, and shredded mozzarella.
  12. Reduce the oven heat to 375 degrees F. Put the spaghetti squash boats back on the baking sheet and bake in the oven for 15-20 minutes, or until cheese is melted and sauce is starting to bubble.
  13. Top each half with some fresh basil and enjoy!

Notes

How to cut spaghetti squash

The outer skin on spaghetti squash is quite tough and hard to cut through. To make it much easier to cut, pierce a few holes in the squash using a fork. Then microwave the whole squash for 3-5 minutes. Then use a sharp knife to cut the squash into two halves the long way.

Storing stuffed spaghetti squash

If you are cooking for yourself, you can store the other spaghetti squash half in the fridge for a day or two after you make it. Store it upright in an airtight container, or on a plate covered with tin foil.

Reheat it in the oven at 300 degrees F for about 20 minutes, until it is hot and cheese is melted.

Keywords: vegetarian stuffed spaghetti squash, stuffed spaghetti squash, spaghetti squash boats