Baked Sausage Spaghetti Casserole Recipe

If you’re in the mood for comfort food that hits all the right notes—meaty, cheesy, saucy, and downright cozy—I have just the thing for you. This Baked Sausage Spaghetti Casserole Recipe is one of my absolute favorites to make when I want something hearty but fuss-free. Imagine tender al dente spaghetti baked in a rich, savory sausage and mushroom tomato sauce, layered with three kinds of cheese and baked until bubbly and golden. It’s basically a lasagna’s easier, more relaxed cousin, and trust me, this dish has become a family favorite in my kitchen.

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Ingredients You’ll Need

Most of these ingredients are ones you probably have on hand or can find easily. The key is choosing savory sausage and good-quality cheeses that melt nicely. Don’t skip the fresh parsley—it adds a pop of brightness that balances the rich flavors.

• Vermicelli pasta or thin spaghetti: I use thin spaghetti because it layers beautifully and cooks up tender but not mushy.
• Bulk sweet Italian sausage: Removing the casing lets you crumble it perfectly—the sweet version keeps the dish from being too spicy but still full of flavor.
• Shiitake or cremini mushrooms: Mushrooms add earthiness and moisture, helping balance the richness of the sausage.
• Onion: Adds sweetness and depth; I like to use yellow onions for their mild flavor.
• Garlic: A couple cloves go a long way to build aroma and flavor.
• Red pepper flakes: Optional, but I love the subtle heat that lifts the dish.
• Marinara or meatless tomato sauce: I’ve made this with homemade sauce and store-bought—both work great.
• Water: Helps simmer the sauce and keep it from getting too thick before baking.
• Italian seasoning: Classic blend to enhance the Italian vibes.
• Fresh parsley: Adds fresh, herbal brightness right before baking.
• Extra virgin olive oil: For sautéing and greasing the casserole dish.
• Parmesan cheese: A sharp, salty edge that melts beautifully in the sauce and pasta mix.
• Eggs: They help bind the pasta and cheeses together once baked.
• Ricotta cheese: Adds creaminess and a luscious texture between the sauce and mozzarella layers.
• Mozzarella cheese: The melty, gooey topping everyone loves for that perfect baked finish.

Variations

I love how flexible this baked sausage spaghetti casserole recipe is—it’s like a blank canvas for flavors. Depending on what you have on hand or your dietary preferences, you can switch things up without losing the magic.

• Spicy Kick: Swap sweet Italian sausage for spicy Italian sausage, or add extra red pepper flakes if you like a little more heat—I discovered this tweak really wakes up the flavors!
• Vegetarian Version: Skip the sausage and add sautéed bell peppers, zucchini, or eggplant instead; you might want to add a bit more seasoning to keep it robust.
• Cheese Choices: Sometimes I swap half the mozzarella for provolone or fontina for a different melty vibe—it’s a fun way to experiment!
• Gluten-Free: Use gluten-free pasta, and your gluten-free marinara if needed—this dish holds up beautifully with those swaps.

How to Make Baked Sausage Spaghetti Casserole Recipe

Step 1: Get your sauce sizzling

Start by breaking up that bulk sweet Italian sausage into chunks in a large sauté pan, then cook it gently over medium heat. Don’t rush this part—slow cooking renders the fat and builds flavor, and you want to break the sausage into bite-sized crumbles as it browns evenly. Once cooked through and no pink remains, scoop the sausage out and drain the fat from the pan. (A quick tip: never pour hot fat down the drain—it can clog pipes!)

Step 2: Sauté the veggies

In that same pan, toss in your chopped onions and mushrooms. Turn the heat up to medium-high and cook, stirring frequently, until onions turn translucent and mushrooms release some of their liquid. Then add garlic and red pepper flakes, cooking for just about a minute more to wake up those flavors without burning the garlic.

Step 3: Simmer the sauce

Pour in your marinara sauce along with 1 1/2 cups of water to keep things saucy and simmer gently. Add the cooked sausage back in, sprinkle in Italian seasoning and fresh parsley, then reduce to a very low simmer. Let it bubble softly for 10 to 15 minutes while you cook the pasta—this step deepens the flavors nicely.

Step 4: Cook the pasta just right

By now your salted water should be boiling—make sure it’s well salted (about 2 tablespoons for 4 quarts water) because that’s your only chance to season the pasta itself. Boil the pasta uncovered for 5 to 6 minutes until al dente; remember it will keep cooking in the casserole, so avoid overcooking. Drain it and rinse with cold water to stop the cooking process and make it easier to handle.

Step 5: Toss pasta with egg and cheese

Transfer the cooled pasta to a large bowl, drizzle with olive oil, sprinkle with grated Parmesan, and add the beaten eggs. I find it easiest to mix this by hand—tossing everything gently so the eggs coat the pasta and the cheese starts to melt slightly.

Step 6: Layer your casserole

Preheat your oven to 350°F (175°C) and grease a 9×13 inch casserole dish with olive oil. Spread one cup of the sausage sauce evenly across the bottom of the dish, then layer half of your pasta on top. Spoon half the remaining sauce over the pasta, dollop all the ricotta cheese in little mounds, and sprinkle half the mozzarella cheese. Repeat with the rest of the pasta, sauce, and mozzarella to build those layers.

Step 7: Bake to cheesy perfection

Cover your casserole with foil and bake for 40 minutes to allow flavors to meld and everything to heat through. Then remove the foil and bake an additional 20 minutes uncovered so the cheese on top gets wonderfully bubbly and golden. When it comes out of the oven, let it rest at least 10 minutes before slicing—that extra wait helps it set up for cleaner squares and better texture.

How to Serve Baked Sausage Spaghetti Casserole Recipe

Garnishes

I like to sprinkle a little extra chopped fresh parsley or basil on top just before serving—it adds a fresh, vibrant touch and makes the dish look as good as it tastes. Sometimes, I also grate a bit of fresh Parmesan over the slices for an extra cheesy hit.

Side Dishes

Pair this with a crisp green salad tossed with a lemon vinaigrette to cut through the richness nicely. Garlic bread or toasted baguette slices also make perfect dunking companions.

Creative Ways to Present

For a special occasion, I’ve baked individual portions in small ramekins. It feels a bit fancy, and everyone loves having their own personal cheesy casserole. Another fun idea is to sprinkle breadcrumbs mixed with Parmesan on top before baking for a crunchy, golden crust.

Make Ahead and Storage

Storing Leftovers

My family rarely has leftovers, but when we do, I store them in an airtight container in the fridge for up to 3 days. The casserole actually tastes better the next day as the flavors have had time to meld even more.

Freezing

I’ve frozen this casserole several times, usually before baking. Just assemble it, cover tightly with foil and plastic wrap, then freeze for up to 3 months. When ready to eat, thaw overnight in the fridge and bake as directed, adding a bit more time as needed.

Reheating

Reheat individual portions in the microwave or the whole casserole in a 350°F oven, covered with foil, until warmed through. A quick spritz of water on top before reheating helps keep it moist and prevents drying out.

FAQs

Final Thoughts

This Baked Sausage Spaghetti Casserole Recipe holds a special place in my heart because it’s the perfect blend of easy weeknight cooking and comforting, hearty flavors. I love pulling it out whenever I want something that feels like a big, warm hug but without a lot of hands-on stress. You’ll find that it pleases both kids and adults alike, plus it makes great leftovers. Give it a try, and I promise you’ll want to make it over and over—just like I do!

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