Easy Low Carb Keto Crustless Pizza Casserole

The smell of Italian sausage browning in a cast iron skillet always takes me back to my tiny first apartment, where I discovered that pizza flavors didn't actually need a crust to be completely satisfying. My roommate walked in during that first experimental batch, suspicious of the "pizza casserole" concept, but left with a empty container and a request for the recipe. Now it's the dish I make when I want all the comfort of Friday night pizza delivery without deciding between carbs and feeling amazing afterward.

Last winter during a snowed-in weekend, my sister called complaining about her failed attempts at keto cooking. I talked her through this recipe over the phone, and when she finally made it, she texted me a picture of her husband scraping the last bits from the pan. The best part is how customizable it becomes, my nieces now request their own versions with extra mushrooms or without green peppers.

Ingredients

• 1 lb ground Italian sausage: The fennel and herbs in Italian sausage create that authentic pizza flavor profile, but ground beef or turkey work perfectly if that is what you have on hand
• 20 slices pepperoni: Optional but recommended because they crisp up beautifully in the oven and add that classic pizza element everyone recognizes
• 1 cup sliced mushrooms: These release moisture as they cook, blending into the sauce and creating an extra savory depth
• 1/2 cup diced green bell pepper: Adds crunch and fresh flavor that cuts through all the rich cheese
• 1/2 cup diced onion: The foundation of flavor, cook it until it is translucent and sweet
• 2 cloves garlic: Minced fresh garlic makes a huge difference here, add it after the vegetables have softened so it does not burn
• 1 cup sugar-free pizza sauce: Check labels carefully because some marinara sauces have surprising amounts of added sugar
• 2 cups shredded mozzarella: The main cheese melt, low moisture mozzarella gives you those perfect cheese pulls
• 1/2 cup shredded cheddar: Adds extra sharpness and helps create that golden brown crust on top
• 1/4 cup grated Parmesan: Sprinkle this on last for a salty, umami-rich finish that browns beautifully
• 1 tsp dried Italian herbs: Even with Italian sausage, this herb blend ties everything together
• 1/2 tsp salt and black pepper: Taste as you go because the sausage and Parmesan both bring saltiness
• Red pepper flakes: Add these at the end if you want a little heat without overwhelming the other flavors

Instructions

Preheat and prep your oven:

Set your oven to 400°F and grab a 9x9 baking dish, give it a quick spray with cooking oil or rub it with a little olive oil

Brown the sausage:

Cook the Italian sausage in a large skillet over medium heat until it is no longer pink, breaking it up with your spoon as it cooks

Sauté the vegetables:

Toss in the mushrooms, peppers, onions, and garlic, letting everything cook together for 3 to 4 minutes until the vegetables have softened and the kitchen smells incredible

Build the flavor base:

Pour in the pizza sauce and sprinkle in the Italian herbs, salt, and pepper, letting everything simmer for just 2 to 3 minutes so the flavors can get friendly

Transfer to baking dish:

Pour the whole sausage and vegetable mixture into your prepared baking dish, spreading it into an even layer

Layer the cheese:

Sprinkle the mozzarella and cheddar evenly across the top, then finish with the Parmesan and arrange pepperoni slices over everything

Bake until bubbly:

Slide it into the oven for 20 to 25 minutes, you will know it is done when the cheese is melted and starting to turn golden brown in spots

Rest before serving:

Let the casserole sit for 5 minutes before digging in, this helps everything set and makes serving much easier

Save

This recipe has saved me on countless busy weeknights when takeout seemed like the only option, and it has become my go-to contribution to potlucks because it disappears faster than anything else I make. There is something satisfying about serving people a dish that tastes indulgent but secretly fits into a healthy lifestyle.

Making It Your Own

The beauty of this crustless pizza concept is how easily it adapts to whatever you have in the refrigerator or whatever your family prefers. I have made versions with black olives, spinach, or even roasted red peppers when the garden was overflowing with them last summer.

Perfect Pairings

A crisp green salad with an acidic vinaigrette cuts through all the rich cheese and balances the meal perfectly. Sometimes I serve it with roasted broccoli or zucchini for extra vegetables, and my kids prefer it with simple steamed green beans.

Storage and Reheating

This casserole meal preps beautifully and actually tastes better the next day as the flavors have more time to meld together. Store it in the refrigerator for up to 4 days or freeze individual portions for those nights when cooking feels impossible.

• Reheat individual portions in the microwave for 2 to 3 minutes, or cover the whole dish with foil and warm it in a 350°F oven until heated through
• Let frozen portions thaw overnight in the refrigerator before reheating for the best texture
• If the cheese seems dry after refrigerating, sprinkle a little water over the top before reheating to restore moisture

Save

Whether you are strictly keto or just looking for a comforting dinner that will not leave you feeling heavy, this pizza casserole has your back.

Recipe Q&A

→ Can I make this casserole ahead of time?

Yes, assemble the entire casserole up to 24 hours in advance and refrigerate unbaked. Add 5-10 minutes to the baking time if cooking from cold. Leftovers reheat beautifully in the microwave or oven.

→ What can I substitute for Italian sausage?

Ground beef, turkey, or plant-based crumbles work well. For authentic Italian flavor, add additional fennel seeds, garlic powder, and red pepper flakes to plain ground meat.

→ Is this casserole freezer-friendly?

Absolutely. Wrap the cooled casserole tightly in foil and freeze for up to 3 months. Thaw overnight in the refrigerator before reheating at 350°F until hot throughout.

→ Can I add other vegetables?

Black olives, spinach, roasted red peppers, or diced zucchini make excellent additions. Just keep vegetable quantities balanced so the cheesy topping still shines through.

→ How do I keep the net carbs low?

Use certified sugar-free pizza sauce and check sausage labels for hidden fillers. The vegetables naturally contribute minimal carbs, while the cheese and protein provide satisfying richness.

→ What size baking dish works best?

A 9x9-inch square pan creates ideal layers with the right thickness. An 11x7-inch rectangular dish or deep pie plate also works well for this quantity.