Sausage Peppers Spaghetti Squash

The first time I made spaghetti squash, I stood in my kitchen completely fascinated by how those strands actually appeared. It felt like kitchen magic, especially when the sweet smell of roasting squash filled my entire apartment. My roommate walked in and asked what pasta dish I was making, not believing me when I said it was actually a vegetable.

Last winter, my sister was doing a low-carb experiment and feeling completely deprived of her favorite Italian dishes. I made this casserole for her birthday dinner instead of the usual lasagna, and she honestly liked it better. The way the squash strands soak up that spiced tomato sauce while getting all melty with cheese is something special.

Ingredients

• 1 large spaghetti squash: Look for one that feels heavy for its size with a hard, unblemished skin, about 3 pounds
• 1 red bell pepper and 1 yellow bell pepper: The combination of both colors adds sweetness and makes the dish look gorgeous
• 1 small yellow onion: Thinly sliced so it softens nicely while cooking with the peppers
• 2 cloves garlic: Minced fresh because jarred garlic just does not work the same way here
• 12 oz Italian sausage: Remove the casings so you can break it up into crumbles while cooking
• 1 1/2 cups marinara sauce: Use your favorite brand or homemade, just check that it is gluten-free if needed
• 1 cup shredded mozzarella and 1/4 cup grated Parmesan: Split these in half, half goes inside and half forms that golden cheese crust on top
• 2 tbsp olive oil: One tablespoon for roasting the squash and one for cooking the sausage mixture
• 1/2 tsp dried oregano and 1/2 tsp dried basil: Classic Italian herbs that reinforce the familiar flavors
• 1/4 tsp crushed red pepper flakes: Optional, but I always add them even when using mild sausage for just a hint of warmth
• Salt and black pepper: Season the squash before roasting and taste the filling before baking
• Fresh basil: For garnish, it makes such a difference in the final presentation

Instructions

Get the oven going and roast that squash:

Preheat your oven to 400 degrees and line a baking sheet with parchment paper. Cut the spaghetti squash in half lengthwise, scoop out the seeds, brush the cut sides with olive oil, and season with salt and pepper. Place them cut side down on the baking sheet and roast for 35 to 40 minutes until tender.

Cook the sausage while the squash roasts:

Heat the remaining olive oil in a large skillet over medium heat. Add the sausage and cook, breaking it up with a spoon, until browned and cooked through.

Add the vegetables and build flavor:

Add the sliced onions and bell peppers to the skillet and sauté for 5 minutes until softened. Stir in the garlic, oregano, basil, and red pepper flakes and cook for one more minute until fragrant.

Create the sauce mixture:

Pour in the marinara sauce and let everything simmer together for 5 minutes. Remove from heat and let it hang out while you handle the squash.

Scrape the squash strands:

Once the squash is cool enough to handle, use a fork to scrape the flesh into spaghetti like strands. Discard the skins and reduce your oven temperature to 375 degrees.

Mix everything together:

In a large bowl, combine the squash strands, sausage mixture, half the mozzarella, and half the Parmesan. Mix well and taste it to see if it needs any additional seasoning.

Assemble and bake the casserole:

Transfer the mixture to a greased 9 by 13 inch baking dish. Top with the remaining mozzarella and Parmesan, then bake uncovered for 15 to 20 minutes until bubbly and golden.

Let it rest and serve:

Let the casserole rest for 5 minutes before garnishing with fresh basil. This helps it set up slightly so it serves more cleanly.

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This dish became my go to for meal prep because it actually reheats beautifully. My husband has been known to eat the leftovers cold straight from the container, which I cannot recommend but does speak to how good it is.

Make It Your Own

I have made this with spicy Italian sausage when I wanted extra kick, and it transforms into something completely different but equally delicious. Sometimes I throw in a handful of spinach to the sausage mixture just before adding the sauce, wilting it down for an extra veggie boost.

Timing Tricks

You can roast the squash a day ahead and keep the strands in the refrigerator. The sausage mixture can also be made in advance, which means weeknight dinner just becomes assembly and baking time.

Serving Ideas

A simple green salad with balsamic vinaigrette balances the richness perfectly. If you are not strictly low carb, some crusty garlic bread on the side would not be out of place.

• Let the casserole rest before cutting or it will not hold its shape
• The top cheese layer can go from golden to burnt quickly, so keep an eye on it during the last few minutes
• This freezes well for up to three months if you want to double the recipe

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Hope this becomes a regular rotation in your kitchen like it has in mine. There is something so satisfying about a casserole that feels indulgent while actually being pretty wholesome.

Recipe Questions & Answers

→ How do you roast spaghetti squash properly?

Slice it in half lengthwise, remove seeds, brush with olive oil, and roast cut-side down at 400°F for 35-40 minutes until tender and strands pull away easily.

→ Can I use a different sausage type?

Yes, plant-based or turkey sausage can be substituted for a lighter or vegetarian option without losing flavor.

→ What is the best way to mix the casserole ingredients?

After roasting and scraping the squash, combine it with the cooked sausage mixture and half the cheese before transferring to the baking dish for an even blend.

→ How long should the casserole bake?

Bake uncovered at 375°F for 15-20 minutes until the cheese on top is melted and golden.

→ Can this dish be prepared ahead of time?

Yes, assemble the casserole in advance and bake just before serving for convenience and fresh taste.