One Pan Zucchini Sausage Casserole – Keto Friendly

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If you’re craving a cozy comfort without the carbs, this One-Pan Zucchini Sausage Casserole delivers.

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It’s hearty, cheesy, and packed with flavor from savory sausage, tender zucchini, and just the right blend of herbs and spices, all baked together in one pan for easy prep and even easier cleanup. 

The best part? This dish fits perfectly into a keto diet while still tasting like real comfort food. There’s no pasta, no breadcrumbs, and no fillers – just wholesome, low-carb ingredients that create a delicious, flavorful casserole the entire family will enjoy, even picky eaters.

• Prep time: 15 minutes
• Cook time: 40 minutes
• Servings: 4 to 6
• Prep level: Beginner +

Ingredient Notes

• Zucchini: Tender, mild, and perfect for soaking up flavor. Use only zucchini or use a combination of zucchini and yellow squash. It adds color and a slightly sweeter flavor to the casserole.
• Type of sausage: Mild ground sausage adds rich, savory flavor with classic Italian seasoning without too much heat, making it perfect for the whole family. Variations – use hot Italian sausage for a little spice, ground chicken, or turkey. Instead of ground meat, sliced sausage links can be used as an alternative
• Onion: Adds natural sweetness and depth. Swap with shallots for a milder flavor, or reduce the amount slightly to lower carbs further.
• Bell pepper: Use red, orange, or yellow for color and subtle flavor. Use a green bell pepper for a sharper, slightly bitter flavor.
• Garlic: Fresh cloves are the best. Thinly sliced or roughly chopped.
• Keto-friendly marinara: Adds saucy richness without hidden sugars. My favorite tomato sauce is Yo-Mama’s Marinara. It’s made with fresh ingredients, contains no added sugar, and is lower in sodium. It’s also made in the Tampa Bay area, which is home to me. 
• Type of cheese: A cheese blend makes the casserole have better flavor depth and texture. Use cheeses that melt well and are creamy. Use block cheese for the best result. Packaged pre-shredded is coated with anti-caking agents, which keep it from melting smoothly.

Step-by-Step Instructions

• Prep the zucchini: Rinse, pat dry, and cut off the tops and ends. Make zucchini noodles with a countertop or handheld spiralizer. You can also use zucchini slices (about 1/8″). Microwave 2-3 minutes, drain well, pat dry, and set aside.
• Chop the vegetables: Use larger pieces for a chunkier casserole, or dice the bell pepper and onion into smaller pieces if you prefer. 

• Brown the sausage: Heat olive oil in a cast-iron skillet over medium heat. Cook the ground sausage until fully cooked. Transfer to a dish and set aside.
• Cook the veggies: Add more oil to the pan if needed. Stir in chopped sweet onion and red bell pepper. Cook until softened. Add the sliced garlic and cook a bit longer.

• Combine everything: Pour in the marinara sauce, return the cooked sausage, and sprinkle in the Italian seasoning, salt, and pepper. Mix well.

• Carefully fold in the zucchini noodles and the fresh basil (if using). Mix until everything is coated evenly. Simmer for a few minutes.

• Add the cheese blend: Sprinkle the mozzarella, Parmesan, and Fontina cheese evenly over the top. For extra cheesiness, gently stir a small handful into the mixture before topping.
• Bake: Transfer skillet to the oven and bake until bubbly.
• Rest and serve: For best results, let the casserole rest before serving.

​See measurements and full recipe below.

Laura Belle’s Top Tip

Once you’ve made the zucchini noodles, roughly cut them into smaller 6 to 8-inch strips. It doesn’t have to be precise; it just makes serving a little easier.

Fresh & Flavorful Side Ideas

• This zucchini casserole is hearty enough to stand on its own, but I like adding something simple on the side to round things out. A crisp green salad with a vinaigrette balances all that cheesy goodness nicely. 
• Want something warm? Steamed broccoli or roasted Brussels sprouts are easy and pair beautifully. And if you’re all about soaking up that extra sauce, a slice of keto cottage cheese bread from Life Currants Blog does the trick!

Storage & Reheating Tips

To Store

• Let the casserole cool completely before storing.
• Transfer to an airtight container.
• Refrigerate for up to 3-4 days.
• For the best texture, store in individual portions for easy grab-and-go meals.

Reheating

• Best method – Reheat in a 350°F oven for 10-15 minutes until warmed through.
• Quick microwave option – Heat in 30-45 second intervals, stirring if needed. If there’s extra moisture, simply drain it off before serving.

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Yield: 4 to 6 servings

One Pan Zucchini Sausage Casserole – Keto Friendly

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This one-pan casserole is packed with mild ground sausage, zucchini noodles, marinara, and melty cheese. Easy, low-carb, and perfect for a busy weeknight dinner the whole family will love.

Prep Time 15 minutes

Cook Time 40 minutes

Total Time 55 minutes

Ingredients

• 2 large zucchini
• 1 large yellow / summer squash
• 2 teaspoons olive oil – divided
• 1 pound mild ground Italian sausage (ground turkey, beef, or chicken)
• 1 bell pepper (red, orange, or yellow) chopped
• 1 large chopped onion – approximately 1.5 cups
• 3-4 garlic cloves, thinly sliced or roughly chopped
• 16 ounces of keto-friendly marinara (tomato sauce)
• 1 teaspoon Italian seasoning
• 1/2 teaspoon salt
• 1/2 teaspoon ground black pepper
• 5-6 fresh basil leaves, roughly chopped – optional
• 2 ounces each – mozzarella, Parmesan, and Fontina cheese – shredded

Instructions

1. Preheat the oven to 375°F.
2. Chop the onion, bell pepper, garlic, and basil. Set aside.
3. Shred the cheese and set it aside.
4. Rinse, pat dry, and cut off the tops and ends. Make zucchini noodles with a countertop or handheld spiralizer. You can also use zucchini slices (about 1/8″). Microwave 2-3 minutes. One microwaved, transfer the zucchini to a strainer and let it cool slightly, then gently press with paper towels to remove extra liquid. This step keeps your casserole from getting too watery. 
5. Heat a large cast-iron skillet and add a teaspoon of olive oil. Add the ground sausage and cook, breaking it up as it browns, until fully cooked and no longer pink. Use a slotted spoon to transfer to a dish and set aside.
6. Drizzle the other teaspoon of oil into the skillet if needed. Add the chopped onion and bell pepper. Cook for 6-8 minutes until softened. Stir in the garlic and cook for another 30 seconds, just until fragrant.
7. Pour in the marinara sauce and return the cooked ground sausage to the skillet.
8. Sprinkle in the Italian seasoning, salt, and pepper. Stir until everything is combined.
9. Gently fold in the zucchini noodles. Mix until fully incorporated and simmer for 5 minutes to let the flavors come together.
10. ​Fold in the chopped fresh basil (if using).
11. Sprinkle the cheeses over the top of the casserole. For extra cheesiness, gently stir a small handful into the mixture before topping.
12. Transfer the cast-iron skillet directly to the oven. Bake for 15-20 minutes, or until the cheese is melted, bubbly, and slightly golden.
13. Let the casserole rest 5-10 minutes before serving.

Notes

• This low-carb dinner can be made in a large skillet on a stovetop, then transferred to a casserole dish, topped with cheese, and baked for 15-20 minutes at 375°F.
• Mozzarella, Fontina, and Parmesan cheese are great choices. Monterey Jack, Gruyère, or even white cheddar cheese are good alternatives. Use full-fat cheese. Full-fat mozzarella and Fontina melt better and release less water than reduced-fat versions.

Nutrition Information:

Yield:

4

Serving Size:

1
Amount Per Serving: Calories: 589Total Fat: 41gSaturated Fat: 15gUnsaturated Fat: 26gCholesterol: 83mgSodium: 1740mgCarbohydrates: 27gFiber: 7gSugar: 15gProtein: 31g

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