This casserole takes all the flavors of a classic pepperoni pizza — sausage, tomatoes, mushrooms, mozzarella, and pepperoni — and layers them into a low-carb, crust-free bake. Rather than building on dough, each component is cooked separately first (browned sausage, drained tomatoes, sautéed mushrooms) and then layered in a casserole dish, topped with cheese and pepperoni, and baked until golden and bubbly. The result is comfort food with real pizza flavor, minus the carbs from a traditional crust.

The recipe yields 6 servings and takes about 50 minutes total, split fairly evenly between stovetop prep and oven baking. Because everything is prepped in stages before assembly, it’s a straightforward recipe to follow even though there are several small components involved.

Getting Everything Ready

Because several components — tomatoes, sausage, and mushrooms — are each prepared separately before layering, having everything prepped in parallel where possible keeps the process efficient.

Equipment to have ready:

• An 8-inch x 11-inch glass casserole dish
• A colander
• Paper towels
• A large non-stick frying pan
• A potato masher (or similar tool for breaking up sausage)

Ingredients to have ready:

• 1 can (14.5 oz.) diced tomatoes, well drained (not petite dice)
• 5 links uncooked turkey or pork Italian sausage (19.5 oz.)
• 2 tsp. + 2 tsp. olive oil
• ½ tsp. dried oregano
• Salt and fresh-ground pepper, to taste
• 12 oz. fresh mushrooms, washed and cut into thick slices (Cremini mushrooms work well)
• 1½ cups grated mozzarella cheese
• 15 slices pepperoni, cut in half (regular or turkey pepperoni)

Draining and drying the canned tomatoes thoroughly before they go into the casserole is a genuinely important step here — rinsing them in a colander and then blotting or air-drying on paper towels removes excess liquid that would otherwise make the finished casserole watery.

Workflow: How the Process Comes Together

This recipe moves through several components prepared in sequence, then assembled into layers:

1. Preheat the oven and prepare the casserole dish.
2. Rinse and dry the canned tomatoes.
3. Brown the sausage in a pan, breaking it apart as it cooks.
4. Layer the sausage, then the drained tomatoes, into the casserole dish, seasoning as you go.
5. Sauté the mushrooms in the same pan until browned.
6. Layer the mushrooms over the sausage-tomato base.
7. Top with mozzarella and pepperoni.
8. Bake until golden and bubbly.

Because the tomatoes need time to drain and dry while the sausage cooks, and the mushrooms can be sautéed in the same pan right after the sausage, working through these steps in an overlapping sequence — rather than one at a time from scratch — keeps the total prep time efficient.

Approved Variations & Swaps

Based strictly on what’s built into this recipe, here are the adjustments it already allows for:

• Sausage type: turkey or pork Italian sausage can both be used.
• Mushroom variety: Cremini (brown) mushrooms are used in the original, though the recipe doesn’t restrict this to a single specific variety.
• Pepperoni type: regular pepperoni or turkey pepperoni can both be used.
• Tomato type: standard diced tomatoes are specified, with a direct note not to use petite dice tomatoes instead.
• Salt level: salt is explicitly noted as a to-taste ingredient, with the original recipe using a light hand.

No other ingredient substitutions are specified in the source recipe, so changes beyond these listed swaps would go beyond what’s actually described here.

Step-by-Step Layering and Baking Strategy

A handful of specific technique choices are what keep this casserole from turning watery or unevenly cooked.

Rinse and thoroughly dry the canned tomatoes before using them. Draining in a colander, then spreading on paper towels or blotting dry, removes excess liquid from the canning process — skipping this step is one of the most direct ways to end up with a watery casserole once everything bakes together.

Remove the sausage from its casing before cooking. Squeezing it out and browning it loose in the pan, breaking it apart as it cooks (a potato masher works well for this), creates the crumbled texture that layers evenly rather than staying in large clumps.

Cook the sausage until nicely browned. Good browning here builds flavor that carries through the rest of the dish, so this isn’t a step to rush.

Layer sausage first, then tomatoes, seasoning as you go. Building the base in this specific order — sausage on the bottom, tomatoes spread over the top, then oregano, salt, and pepper — sets up the rest of the layers to sit properly without the seasoning getting buried.

Sauté the mushrooms until their liquid fully releases and they start to brown. Mushrooms hold a lot of water, and cooking them until that liquid has cooked off and they begin to brown is what prevents them from adding excess moisture to the casserole later — stopping too early leaves them watery and pale rather than flavorful.

Reuse the same pan for the mushrooms, rinsing if needed. This keeps cleanup simple and takes advantage of any residual flavor left in the pan from the sausage.

Space the pepperoni evenly across the cheese layer. Covering the whole top evenly, rather than clustering pepperoni in one area, ensures every serving gets a fair share of that classic pizza topping.

Bake until the cheese is both melted and starting to brown. About 25 minutes is the guide, but watching for that visual browning on top is the more reliable indicator that the casserole is fully heated through and ready to serve.

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Low-Carb Deconstructed Pizza Casserole

Description: A comfort food casserole that layers all the flavors of pepperoni pizza — sausage, tomatoes, mushrooms, mozzarella, and pepperoni — into a low-carb, crust-free bake. A family-friendly favorite that comes together in under an hour.

Duration:

• Yield: 6 servings
• Prep Time: 25 minutes
• Cook Time: 25 minutes
• Total Time: 50 minutes

Ingredients

• 1 can (14.5 oz.) diced tomatoes, well drained (do not use petite dice tomatoes)
• 5 links uncooked turkey or pork Italian sausage (19.5 oz.)
• 2 tsp. + 2 tsp. olive oil
• ½ tsp. dried oregano
• Salt and fresh-ground pepper, to taste
• 12 oz. fresh mushrooms, washed and cut into thick slices (Cremini mushrooms recommended)
• 1½ cups grated mozzarella cheese
• 15 slices pepperoni, cut in half (regular or turkey pepperoni)

Instructions

1. Preheat the oven to 400°F (200°C). Spray an 8-inch x 11-inch glass casserole dish with non-stick spray or olive oil.
2. Pour the diced tomatoes into a colander and rinse with cold water. Let drain a minute or two, then spread out on paper towels to dry, or blot dry with another paper towel on top.
3. While the tomatoes dry, heat 2 tsp. olive oil in a large non-stick frying pan. Squeeze the sausage out of its casing and cook over medium-high heat until nicely browned, breaking it apart as it cooks.
4. While the sausage cooks, wash the mushrooms, pat dry, and slice into thick pieces.
5. Layer the cooked sausage in the bottom of the casserole dish, then top with the drained tomatoes, spreading evenly. Season with oregano, salt, and pepper.
6. Rinse the pan if needed, then heat the remaining 2 tsp. olive oil over medium-high heat. Add the mushrooms and cook, stirring occasionally, until all liquid is released and they start to brown.
7. Layer the mushrooms over the sausage-tomato mixture.
8. Cut the pepperoni in half.
9. Sprinkle the grated mozzarella over the top of the casserole and lay the pepperoni pieces evenly over the cheese, covering the whole top.
10. Bake about 25 minutes, or until the cheese is melted and starting to brown. Serve hot.

Notes

• Do not use petite dice tomatoes; standard diced tomatoes work best for this recipe.
• Draining and drying the tomatoes thoroughly helps prevent a watery casserole.
• Turkey or pork sausage, and regular or turkey pepperoni, can both be used interchangeably.
• Nutrition per serving: 289 kcal, 18g total fat, 7g saturated fat, 10g unsaturated fat, 85mg cholesterol, 561mg sodium, 6g carbohydrates, 2g fiber, 3g sugar, 26g protein.

Disclaimer: This recipe is provided for general informational purposes only and does not constitute medical or dietary advice. Nutritional values are estimates and may vary based on specific ingredients and brands used, and the sodium content is relatively high per serving. Individuals with food allergies, dietary restrictions, or specific health conditions (including but not limited to dairy sensitivities or conditions requiring sodium restriction) should consult a qualified healthcare provider or registered dietitian before preparing or consuming this recipe. This recipe involves raw meat and requires cooking to a safe internal temperature; please take appropriate food safety precautions. Neither the author nor the publisher assumes responsibility for any adverse effects resulting from the preparation or consumption of this recipe.