Name: Keto Philly Cheesesteak Casserole Recipe
Prep time: 15 min
Cook time: 30 min
Total time: 45 min
Cuisine: American
Ingredients: 1 large green bell pepper; 1 large yellow bell pepper; 1 large red bell pepper; 1 small onion, thinly sliced (about ½ cup); 8 ounces cremini mushrooms, thinly sliced; 3 cloves garlic, minced; 2 tablespoons salted butter; 6 slices provolone cheese (about 6 ounces); 1 cup shredded mozzarella cheese; 1 ½ pounds deli-style roast beef, thinly sliced

Jump to Recipe· 4.4 from 15 reviews

If you have a craving for all the rich, hearty flavors of a classic Philly cheesesteak but want to keep it low-carb and gluten free, this Keto Philly Cheesesteak Casserole Recipe is about to become your new go-to. Bursting with tender slices of roast beef, vibrant bell peppers, sweet onions, and earthy mushrooms, all wrapped in layers of melty provolone and mozzarella, this dish delivers that satisfying cheesesteak taste without the bun. What I love most is how quickly it comes together and that it only requires one pan—talk about a weeknight dinner winner that doesn’t keep you chained to the kitchen!

Ingredients You'll Need

The image shows six white dishes and two garlic cloves on a white marbled surface. At the top right, a white plate is filled with thin, folded slices of cooked roast beef in brown and pink shades. Below and slightly left, a round white bowl holds bright red, green, and yellow sliced bell peppers with a shiny texture. Below that, another white bowl contains light to medium brown mushroom slices with smooth caps. At the bottom center, a small white plate has four round, pale yellow cheese slices stacked neatly. To the right, a small white bowl is filled with shredded white cheese. To the left of the cheese plate, a small brown onion lies on the surface. Near the peppers is a small white bowl holding three pale yellow cubes of butter. Close to it are two garlic cloves with white and light brown skins. The setup has a clean, organized look with soft natural light illuminating the ingredients from above. photo taken with an iphone --ar 4:5 --v 7

The beauty of the Keto Philly Cheesesteak Casserole Recipe lies in its simplicity—the ingredients are straightforward but each one plays a key role in building layers of flavor, texture, and color that make this casserole so irresistible. From the brightness of fresh bell peppers to the luscious creaminess of melted cheeses, every bite is a delight.

1 large green bell pepper: Adds a crisp, slightly grassy crunch that balances the meatiness.

1 large yellow bell pepper: Brings a touch of sweetness and sunny color to the medley.
1 large red bell pepper: Offers vibrant color and a naturally sweet flavor that contrasts wonderfully with savory elements.
2 tablespoons salted butter: Provides richness and is perfect for sautéing the veggies to perfection.

1 small onion, thinly sliced (about ½ cup): Infuses a subtle sweetness as it softens and caramelizes slightly.
3 cloves garlic, minced: Packs an aromatic punch that lifts the whole dish.
8 ounces cremini mushrooms, thinly sliced: Adds earthiness and a meaty texture that complements the roast beef.

1 ½ pounds deli-style roast beef, thinly sliced: The star protein, tender and full of flavor that makes this casserole hearty and filling.
6 slices provolone cheese (about 6 ounces): Melts beautifully and lends that classic cheesesteak cheesiness.
1 cup shredded mozzarella cheese: Sprinkled on top to create a bubbly, golden crust that's irresistibly gooey.

How to Make Keto Philly Cheesesteak Casserole Recipe

Step 1: Prepare the Vegetables

Start by cutting the tops off all three bell peppers and removing the ribs and seeds—this ensures each slice is crisp and free of bitterness. Then, thinly slice the peppers to create those signature cheesesteak strips. Setting these aside allows you to focus on softening the aromatics next.

Step 2: Sauté the Onion and Garlic

Heat the salted butter in a large, deep-sided ovenproof skillet or Dutch oven over medium-low heat. Add your thinly sliced onions and minced garlic, cooking gently until the onions become translucent and the garlic releases its mouthwatering aroma. This process takes about seven minutes and is essential for layering that subtle sweetness and fragrant depth.

Step 3: Cook the Mushrooms and Peppers

Next, add the sliced mushrooms and bell peppers into the skillet. Let them cook, stirring occasionally, until the mushrooms release their moisture and the peppers turn crisp-tender—roughly 10 minutes. This step beautifully softens the vegetables while maintaining a bit of bite, which is just the right texture for this casserole.

Step 4: Combine Roast Beef and Vegetables

Preheat your oven to 350°F (175°C) while you add the thinly sliced roast beef to the skillet. Gently toss it with the cooked veggies, letting the beef warm through and absorb those wonderful flavors. Give it a quick taste, adjusting with salt and pepper if needed. Then, neatly layer the six slices of provolone cheese over the top, followed by an even sprinkle of shredded mozzarella.

Step 5: Bake and Broil to Perfection

Place the skillet in the oven and bake for 15 minutes, allowing the cheese to melt evenly and the flavors to meld together. For that irresistible bubbly and slightly browned top, switch your oven to the broiler setting and cook for an additional 2 to 3 minutes—just keep a close eye so it doesn’t burn. What you end up with is a dreamy, gooey, and savory casserole that screams comfort food in the best way possible.

How to Serve Keto Philly Cheesesteak Casserole Recipe

A white pot filled with a layered dish, the top layer is melted cheese with a light golden brown color, slightly bubbly and covering thin slices of red and yellow bell peppers visible underneath. Below the cheese, there are shredded pieces of cooked meat mixed with small brown mushrooms and slices of bell peppers in red, yellow, and orange. A wooden spoon is scooping out a portion from the right side, showing the layered texture inside. The pot is placed on a white marbled surface with a yellow cloth nearby and a green glass with bubbles and another bowl of food blurred in the background. Photo taken with an iphone --ar 4:5 --v 7

Garnishes

To elevate your Keto Philly Cheesesteak Casserole Recipe even further, a sprinkle of freshly chopped parsley or green onions adds a pop of color and freshness. If you like a little kick, a few red pepper flakes or a drizzle of your favorite hot sauce can balance the creamy cheese with a touch of heat.

Side Dishes

This casserole is wonderfully filling on its own, but pairing it with a crisp green salad dressed with tangy vinaigrette helps cut through the richness. Roasted or steamed low-carb vegetables such as asparagus or broccoli also complement the hearty flavors without overwhelming the ketosis-friendly profile.

Creative Ways to Present

For a fun twist, serve the casserole in individual ramekins or mini cast iron skillets for a charming presentation perfect for dinner parties or family meals. You can also scoop it over a bed of cauliflower rice or keto-friendly cauliflower mash to make it a complete low-carb feast.

Make Ahead and Storage

Storing Leftovers

The Keto Philly Cheesesteak Casserole Recipe keeps beautifully in the fridge for up to 3 days when stored in an airtight container. The flavors actually deepen after resting overnight, so leftovers are perfect for quick meals during busy days.

Freezing

If you want to prepare this casserole ahead of time, it freezes wonderfully. Just bake as directed, let it cool completely, then cover tightly with foil or plastic wrap before placing it in the freezer. It will maintain its flavor and texture for up to 2 months.

Reheating

Reheat leftovers gently in the oven at 325°F until warmed through, usually about 15-20 minutes depending on portion size. Avoid the microwave if you want to keep the cheeses melty and the textures close to freshly baked. For a crispy top, throw it under the broiler for a minute or two once heated.

FAQs

Can I use other types of beef for the casserole?

Absolutely! While deli-style roast beef is convenient and tender, thinly sliced ribeye or sirloin can be used if you prefer cooking your own beef. Just sauté it quickly before adding to the casserole for best results.

Is this casserole suitable for gluten-free diets?

Yes! The key ingredients in this keto casserole naturally contain no gluten, making it a safe and delicious option for anyone avoiding gluten.

Can I substitute the cheeses?

Definitely. Provolone and mozzarella provide the classic Philly cheesesteak flavor and great meltability, but you can experiment with fontina, gouda, or even sharp cheddar if you want to switch things up.

How spicy is this recipe?

This casserole is mild by default, focusing on savory and cheesy flavors. You can easily add spice by mixing in diced jalapeños with the peppers or serving it alongside spicy mustard or hot sauce.

Can I make this recipe vegetarian?

While roast beef is the centerpiece here, you could swap it out for extra mushrooms or a plant-based beef substitute to keep the hearty feel and enjoy a vegetarian version.

Final Thoughts

There’s something genuinely comforting about a dish that brings together your favorite flavors with ease and speed, and this Keto Philly Cheesesteak Casserole Recipe ticks all those boxes. Whether you’re cooking for yourself or feeding the family, it’s a simple, satisfying meal that’s full of flavor and low on fuss. I hope you’ll give it a try and make it one of your treasured quick dinners. You’re going to love every cheesy, savory bite!

Keto Philly Cheesesteak Casserole Recipe

Ingredients You'll Need