Name: Sausage and Peppers Spaghetti Squash Casserole
Prep time: 15 min
Cook time: 50 min
Total time: 1 h 5 min
Cuisine: Italian-American
Ingredients: 1 large spaghetti squash; 2 tbsp olive oil; Salt and black pepper; 1 lb Italian sausage; 1 onion, diced; 1 red bell pepper, diced; 1 yellow bell pepper, diced; 3 garlic cloves, minced; 2 cups marinara sauce; 1 tsp Italian seasoning; ½ tsp red pepper flakes; 1½ cups shredded mozzarella; ½ cup grated Parmesan; 2 tbsp fresh basil or parsley

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Sausage and Peppers Spaghetti Squash Casserole – Comfort Food, Lightened Up

This casserole takes all the cozy, satisfying flavors of sausage and peppers and swaps the heavy pasta for tender spaghetti squash strands, giving you comfort without the carb overload. It’s a weeknight-friendly bake with rich marinara, melty cheese, and bright herbs that make leftovers even better. If you enjoy skillet meals with bold flavors, you might also like Cajun Sausage and Rice Skillet for another hearty, one-pan option.

Why make this recipe
If you’re tired of feeling sluggish after big pasta dinners, this casserole is perfect because it cuts calories and carbs without sacrificing the savory sausage-and-pepper flavor you love. It’s an easy way to enjoy a familiar Italian-American combination in a lighter, vegetable-forward format that still feels indulgent. Also, it’s highly adaptable—swap sausage types or tweak the spice to suit your household.

Ingredients

1 large spaghetti squash
2 tbsp olive oil
Salt and black pepper
1 lb Italian sausage
1 onion, diced
1 red bell pepper, diced
1 yellow bell pepper, diced
3 garlic cloves, minced
2 cups marinara sauce
1 tsp Italian seasoning
½ tsp red pepper flakes
1½ cups shredded mozzarella
½ cup grated Parmesan
2 tbsp fresh basil or parsley

Step-by-Step Guide to Making Sausage and Peppers Spaghetti Squash Casserole

Overview of the process
This dish follows three broad steps: roast the spaghetti squash until it’s tender and stringy, make a flavorful sausage-and-pepper sauce, then combine, top with cheese, and bake until bubbly. Each stage is forgiving, so you can make parts ahead and assemble when ready.

Roast the spaghetti squash

Preheat your oven to 400°F (200°C).
Halve the spaghetti squash lengthwise, scoop out the seeds, brush the cut sides with 1 tbsp olive oil, and season with salt and black pepper.
Place the halves cut-side down on a rimmed baking sheet lined with parchment or foil. Roast for 35–40 minutes until the squash is tender and a fork easily pierces the skin.
Allow the squash to cool a few minutes, then use a fork to scrape the flesh into spaghetti-like strands. Place the strands in a colander or a fine mesh sieve and press lightly to remove excess moisture — this prevents a watery casserole.

Make the sausage and pepper mixture

In a large skillet, heat the remaining 1 tbsp olive oil over medium-high heat.
Add the Italian sausage, breaking it up with a spoon. Brown until cooked through and edges are slightly crisp about 6–8 minutes. Drain excess fat if your sausage is very fatty.
Add the diced onion and bell peppers to the skillet and cook until softened, about 4–6 minutes. Stir in the minced garlic and cook for another 30–60 seconds until fragrant.
Stir in the marinara sauce, Italian seasoning, and red pepper flakes. Reduce heat and simmer for 5 minutes to let the flavors meld. Taste and adjust salt and pepper as needed.

Combine and assemble

In a large mixing bowl, combine the roasted and drained spaghetti squash strands with the sausage-and-pepper mixture. Stir in 1 cup of the shredded mozzarella and half the grated Parmesan so the mixture holds together when spooned into the casserole dish.
Lightly oil a 9×13-inch (or similar size) casserole dish and spread the combined mixture evenly into the dish.
Sprinkle the remaining mozzarella and Parmesan evenly over the top.

Bake

Preheat the oven to 375°F (190°C) if it has cooled from earlier steps.
Cover the casserole dish with foil and bake covered for 20 minutes to heat through and let the cheese melt into the strands.
Remove the foil and bake an additional 10 minutes until the top is golden and bubbly.
Allow the casserole to rest for 10 minutes before serving so it sets slightly and is easier to slice.

Finish and serve

Garnish with 2 tablespoons of chopped fresh basil or parsley for brightness and color.
Serve warm with simple sides or a crisp salad.

Detailed timing and useful tips during the cooking process

Roast the squash first: Roasting early allows you to make the sausage filling while the squash cools and drains.
Drain squash well: Excess moisture is the number-one cause of a soupy casserole. After scraping, let the strands sit in a colander and press lightly with paper towels or a clean kitchen towel.
Use a flavorful marinara: A good marinara elevates the whole dish. If your marinara is bland, add a splash of red wine or a pinch of sugar to balance acidity.
Cheese layering: Mixing some cheese into the base gives body to the casserole; finishing with a generous top layer yields the comforting browned, bubbly finish everyone expects.

Best Way to Store Sausage and Peppers Spaghetti Squash Casserole

Refrigerator: Store tightly covered or in an airtight container at 40°F (4°C) or below for up to 3–4 days.
Freezer: Cool completely, then freeze in an airtight container or heavy-duty freezer bag at 0°F (-18°C) for up to 3 months.
Reheating: Thaw overnight in the refrigerator if frozen. Reheat covered in a 350°F (175°C) oven until warmed through (about 20–30 minutes) or microwave individual portions until hot. A sprinkle of fresh cheese and a quick broil for 1–2 minutes will refresh the top.

Serving Suggestions for Sausage and Peppers Spaghetti Squash Casserole

Light salad: A peppery arugula salad dressed with lemon vinaigrette cuts through the richness and makes for a balanced plate.
Crusty bread or garlic toast: For those who want a little more heft, a warm slice of crusty bread is perfect for mopping up sauce.
Roasted vegetables: Serve with a side of roasted broccoli or green beans for extra veg and color.
Wine pairing: A medium-bodied red like Chianti or a fruity Zinfandel complements the sausage and tomato flavors; for white lovers, a rich Chardonnay can work nicely.
Family-style: This casserole is designed to be served family-style straight from the dish—let everyone spoon out a portion and top with extra basil and grated Parmesan.

tips to make Sausage and Peppers Spaghetti Squash Casserole
Q: How can I keep the casserole from getting soggy?
A: Make sure the roasted spaghetti squash is well-drained — press it lightly in a colander or with paper towels to remove excess moisture before mixing with the sausage sauce.

Q: What sausage should I use?
A: Mild or sweet Italian sausage will give you classic sausage flavor without too much heat; spicy Italian sausage adds a nice kick. You can also use turkey sausage for a lighter option, though brown it gently to develop flavor.

Q: Can I prepare this ahead?
A: Yes — assemble the casserole up to the baking step, cover tightly, and refrigerate for up to 24 hours before baking. If frozen, bake from thawed for best texture.

variation(s)

Swap the sausage: Use turkey or chicken sausage to reduce fat and calories. If using ground pork and Italian seasoning, add a pinch more fennel seed to mimic the sausage flavor.
Vegetarian option: Replace sausage with a hearty mushroom medley (cremini, shiitake) sautéed with a touch of smoked paprika and soy sauce for umami. Add a can of drained, rinsed white beans for protein if desired.

FAQs
Q: Can I make this dairy-free?
A: Yes — use a dairy-free marinara and substitute shredded dairy-free mozzarella and Parmesan alternatives or nutritional yeast for a cheesy flavor.

Q: Is it gluten-free?
A: The casserole itself is naturally gluten-free as long as your sausage and marinara are certified gluten-free. Always check labels to be safe.

Q: How do I know when the spaghetti squash is done roasting?
A: The flesh should be tender when pierced with a fork, and the strands should separate easily without resistance.

Are there ways to add more vegetables?

Absolutely. Stir in chopped spinach or kale near the end of the sausage simmer so the greens wilt but retain color. Zucchini or mushrooms can be sautéed with the peppers for extra substance.

How long will it keep reheated?

Reheated in the oven, the casserole should maintain good quality for 2–3 days after refrigeration. Avoid multiple reheating cycles to preserve texture.

Can I make this lower sodium?

Yes — choose a low-sodium marinara and sausage, and omit added salt until the end when you can taste and adjust.

Cooking and ingredient substitutions comparison

Sausage choice: Italian sausage (traditional flavor) vs. turkey sausage (lighter, milder) — Italian sausage gives more depth and fat for richness; turkey sausage reduces calories but may need extra seasoning.
Cheese options: Full-fat mozzarella and Parmesan (creamy and melty) vs. part-skim or dairy-free alternatives (lower fat or dairy-free, but may not brown as deeply).

Meal prep and hosting ideas
This casserole is a great make-ahead centerpiece for a casual dinner party or busy weeknight. Prepare the squash and filling one day ahead, assemble and chill, then slide it into the oven when guests arrive. For buffet-style serving, keep it warm in a low oven (200°F / 95°C) with foil loosely tented.

Nutrition notes
Swapping spaghetti squash for traditional pasta cuts carbohydrates and calories significantly while boosting vitamin A, vitamin C, and fiber. Using lean or turkey sausage further reduces saturated fat. To boost fiber and nutrients, include extra vegetables like spinach or roasted eggplant in the filling.

Troubleshooting

If the casserole is watery after baking: Next time, squeeze more moisture from the cooked squash and consider reducing the marinara slightly while simmering so the sauce is thicker.
If the top browns too fast: Cover with foil while baking until the last 10 minutes, then uncover to allow browning.
If the casserole is bland: Taste the sausage mixture before mixing with the squash and correct with salt, pepper, or a pinch of sugar to balance the acidity.

Final presentation tips
Let the casserole rest 10 minutes before serving for cleaner slices and better mouthfeel. Garnish with fresh herbs and a light drizzle of good-quality extra-virgin olive oil for shine. Offer lemon wedges on the side for those who like an extra bright finish.

Conclusion

This Sausage and Peppers Spaghetti Squash Casserole is a comforting, lighter spin on Italian-American flavors that works beautifully for family dinners, meal prep, and casual entertaining. For more spaghetti squash casserole ideas with a similar lightened-up approach, see this recipe for Swiss Chard & Spaghetti Squash Gratin which uses green leafy vegetables and a creamy, lower-fat preparation. If you want another hearty casserole with a meat sauce twist, try the Turkey Bolognese Spaghetti Squash Casserole Recipe for inspiration and useful techniques.