This casserole is packed with Italian sausage, tender bell peppers and onions, and, of course, lots of melty mozzarella cheese! It’s super quick to throw together, and the recipe is super low carb and keto, too. Our whole family loves it – even the kids.
What Makes This Recipe So Good
- All the goodness of cheesy stuffed peppers baked right into an “unstuffed” pepper casserole! With tangy Italian sausage, melty mozzarella, and crisp peppers and onions, this flavorful entrée will make your whole family happy. Seriously! Even my kids love it.
- This is a great option for meal prepping! It refrigerates well and reheats nicely in the microwave, so it’s perfect for packing into a work lunch. Just refrigerate it in an airtight container up to 5 days. It’s nice and filling, too, so it won’t have you heading for the vending machine an hour later.
- What to serve with this casserole? Anything, really! A small side salad, garlic bread, cauliflower rice, or a little pasta (or palmini noodles if you’re keto). For a veggie-heavy meal, try Italian green beans, sauteed spinach, or the best air fryer broccoli.
Italian Sausage – For this recipe you’ll want to use Italian link sausage or rope sausage, rather than ground Italian sausage. Ground would work, absolutely, but I really like the larger pieces here. You can use mild or hot Italian sausage, too, whatever you prefer!
Mozzarella – As usual, I recommend shredding your own mozzarella. Prepackaged shredded cheese contain fillers and starches that act as anti-clumping agents. They also add unnecessary carbs to the cheese and they keep it from melting as well. For the best results, go with fresh!
- The baking dish you use makes a difference here! You want a shallow, 9×13 baking dish rather than a smaller, deeper casserole dish. That way everything cooks evenly and thoroughly! If the layers are too thick, you’ll end up with some peppers and onions that are more crunchy than tender, and the sausage might not cook completely.
- The sausage shouldn’t be fully cooked in the skillet! You just want to brown it so it gets that delicious crispness. If it’s fully cooked before you mix it into the casserole, you run the risk of it overcooking in the oven.
- The covered + uncovered baking combo is important, so don’t skip the foil. Covering the dish helps insulate it, so all of the layers get good and hot. Uncovering the dish lets the cheese on top get nice and melty, and crisps the sausage and peppers a little more.
More Delicious Casseroles You’ll Love
- Reuben Casserole (Low Carb, Keto Option)
- Creamy Veg-All Casserole
- Cheesy Spinach Casserole
- Keto Broccoli Cauliflower Casserole
- Mexican Chicken Casserole
- Garlic Bread Casserole
- Poppy Seed Chicken
- Sweet Potato Casserole
- 1 ½ pounds Italian sausage link or rope sausage
- ¼ cup tomato paste
- ¼ cup water
- 2 teaspoons Italian seasoning
- 4 large bell peppers various colors; seeds removed, sliced into ½-inch-long pieces
- 1 medium onion halved, sliced into ½-inch-long pieces
- 2 cups freshly shredded mozzarella divided
- ½ teaspoon salt
- fresh basil chopped or chiffonaded; for garnish
- 9×13 baking dish
- Cooking spray
- Large skillet
- Small bowl
- Large bowl (or use the skillet if it's large enough)
- Aluminum Foil
- Preheat oven to 375° Fahrenheit. Spray 9×13 baking dish with cooking spray and set aside. Cut sausage into 1-inch pieces.
- Heat large skillet over medium heat, then add sausage. Cook 10 minutes or so, stirring occasionally, until sausage is browned but not fully cooked through. Drain any liquid from skillet.
- In small bowl, whisk together tomato paste, water, and Italian seasoning, stirring until well combined. Set aside.
- In large bowl (or skillet if large enough), mix together browned sausage, bell peppers, and onions. Pour tomato sauce over sausage and vegetables, then stir well to coat thoroughly.
- Transfer half of sausage mixture to greased baking dish. Top with 1 cup mozzarella. Spread remaining sausage mixture on top of cheese and cover baking dish with foil.
- Place covered baking dish in preheated oven and bake 30 minutes. After 30 minutes, remove foil and stir casserole well. Top with remaining 1 cup mozzarella and return baking dish to oven, uncovered.
- Bake, uncovered, 10 minutes or until sausage is no longer pink and peppers are tender. Remove from oven and serve hot.
- Mozzarella: Shred your own mozzarella from a block of fresh cheese. It melts much better than the pre-shredded version, and it doesn’t contain any added fillers or anti-clumping agents (especially important if you’re low carb or keto!).
- Make it Keto: Be sure your tomato paste doesn’t contain any added sugars or any sugar substitutes that aren’t keto-friendly. Natural sugars from the tomatoes are fine. You also want to make sure the sausage doesn’t contain any sugar and has the fewest carbs possible. Use all green bell peppers rather than a variety of colors; green bell peppers have the fewest carbs.
Number of total servings shown is approximate. Actual number of servings will depend on your preferred portion sizes.
Nutritional values shown are general guidelines and reflect information for 1 serving using the ingredients listed, not including any optional ingredients. Actual macros may vary slightly depending on specific brands and types of ingredients used.
To determine the weight of one serving, prepare the recipe as instructed. Weigh the finished recipe, then divide the weight of the finished recipe (not including the weight of the container the food is in) by the desired number of servings. Result will be the weight of one serving.