This casserole brings all the flavor of a classic mushroom and Swiss burger, minus the bun and the fuss. Think juicy ground beef, caramelized mushrooms and onions, creamy sauce, and a bubbly layer of Swiss cheese. It’s weeknight-friendly, rich without being heavy, and totally satisfying.

If you’re keeping carbs low or just want a hearty, crowd-pleasing dinner, this one checks every box. Make it once, and it’ll land in your regular rotation.

Why This Recipe Works

Simple, familiar flavors: Savory beef and mushrooms pair naturally with Swiss cheese for a classic, burger-inspired bite.
Low-carb without compromise: No fillers, no breadcrumbs, and no grains—just real ingredients that taste great.
One-pan friendly: Brown everything in a skillet, then bake in the same dish. Minimal cleanup, maximum reward.
Balanced texture: A creamy sauce holds it all together, while the cheese on top gets golden and stretchy.
Flexible and forgiving: Easy to customize with different cheeses, veggies, or seasonings without adding carbs.

Close-up detail: A bubbling Keto Mushroom & Swiss Burger Casserole just out of the oven, broiled Swi

Ingredients

1.5 pounds ground beef (80/20 works best)
2 tablespoons butter or avocado oil
10 ounces cremini or button mushrooms, sliced
1 small yellow onion, thinly sliced
3 cloves garlic, minced
1 teaspoon kosher salt, plus more to taste
1/2 teaspoon black pepper
1 teaspoon Worcestershire sauce (check label for sugar; optional)
1 teaspoon Dijon mustard
1/2 teaspoon smoked paprika (optional)
1/2 teaspoon dried thyme or Italian seasoning
4 ounces cream cheese, softened
1/2 cup heavy cream
1/3 cup beef broth (low-sodium)
6–8 slices Swiss cheese (or about 6 ounces shredded Swiss)
Fresh parsley or chives, chopped, for garnish

How To Make Keto Mushroom & Swiss Burger Casserole

Preheat and prep: Heat your oven to 375°F (190°C).
Lightly grease a 9×13-inch baking dish or an oven-safe skillet.
Cook the beef: In a large skillet over medium-high heat, add the ground beef and season with a pinch of salt and pepper. Cook, breaking it up, until browned with no pink remaining, about 6–8 minutes. Drain excess fat if needed, leaving about 1 tablespoon in the pan.
Transfer the beef to a bowl and set aside.
Sauté the vegetables: In the same skillet, add butter or oil. Stir in the onions and mushrooms. Cook over medium heat, stirring occasionally, until the onions are soft and the mushrooms have released their moisture and browned slightly, 8–10 minutes.
Add the garlic and cook for 30 seconds until fragrant.
Add seasonings: Stir in Worcestershire (if using), Dijon mustard, smoked paprika, thyme, 1 teaspoon salt, and 1/2 teaspoon pepper. Cook for 1 minute to bloom the flavors.
Make it creamy: Reduce heat to low. Add the cream cheese and stir until melted and smooth.
Pour in the heavy cream and beef broth, stirring until the mixture is silky and slightly thickened, 2–3 minutes.
Combine with beef: Return the cooked beef and any juices to the skillet. Stir to coat everything in the creamy mushroom sauce. Taste and adjust seasoning.
Assemble: Transfer the mixture to your baking dish (or keep in an oven-safe skillet).
Layer the Swiss cheese evenly over the top.
Bake: Place in the oven and bake for 12–15 minutes, until the cheese is melted and the edges are bubbling. For a golden top, broil for 1–2 minutes at the end, watching closely.
Rest and serve: Let the casserole rest for 5–10 minutes to set. Garnish with chopped parsley or chives.
Slice and serve warm.

Cooking process: Overhead shot of the creamy beef-and-mushroom mixture in an oven-safe skillet right

Storage Instructions

Refrigerator: Store leftovers in an airtight container for up to 4 days. Reheat gently in the microwave or covered in a 325°F oven until warmed through.
Freezer: Cool completely, then portion into freezer-safe containers. Freeze for up to 2 months.
Thaw overnight in the fridge before reheating.
Reheating tip: Add a splash of cream or a small pat of butter when reheating to keep it moist and creamy.

Why This is Good for You

Low in carbs, high in satisfaction: This casserole keeps net carbs minimal while delivering plenty of flavor and satiety.
Protein and healthy fats: Ground beef provides protein, while cream and cheese offer fats to help you feel full longer.
Micronutrients from mushrooms: Mushrooms bring B vitamins, potassium, and antioxidants that support energy and immune health.
Steady energy: Without refined carbs, many people experience fewer blood sugar swings and more consistent energy.

What Not to Do

Don’t rush the mushrooms: If they don’t brown, the flavor will fall flat. Give them time to release moisture and caramelize.
Don’t skip seasoning: The fat and dairy need enough salt and spices to shine. Taste and adjust.
Don’t use ultra-lean beef: A bit of fat equals more flavor and better texture. 80/20 or 85/15 is best.
Don’t drown it in liquid: Too much broth or cream can make it soupy.
Stick to the amounts listed.
Don’t overbake: Once the cheese melts and bubbles, it’s done. Overbaking can cause separation and dryness.

Final plated dish: Restaurant-quality presentation of a square slice of Keto Mushroom & Swiss Burger

Alternatives

Protein swaps: Try ground turkey, chicken, or bison. Add a tablespoon of olive oil if using very lean meats.
Cheese options: Gruyère, provolone, or a blend of Swiss and mozzarella all melt beautifully.
For bolder flavor, add a little Parmesan.
Dairy-free route: Use coconut cream and a dairy-free cream cheese alternative. Top with a good vegan “Swiss-style” melt.
Add greens: Stir in a handful of chopped spinach or kale during the creamy step. They wilt quickly and add color and fiber.
Extra low-carb bulk: Serve over steamed riced cauliflower or roasted zucchini planks for a heartier plate.
Spice it up: Add red pepper flakes or a splash of hot sauce to the sauce.
You can also sauté a diced jalapeño with the onions.

FAQ’s For Keto Mushrooms & Swiss Burger Casserole

How many carbs are in a serving?

Exact carbs depend on brands and portion size, but a typical serving lands around 4–6 net carbs. Check labels and calculate if you track macros closely.

Can I make this ahead of time?

Yes. Assemble up to the cheese topping, cover, and refrigerate for up to 24 hours. Bake straight from the fridge, adding a few extra minutes until bubbly.

What can I use instead of mushrooms?

You can swap mushrooms for diced zucchini or sautéed bell peppers. Keep the pieces small and cook off excess moisture before assembling.

Is Worcestershire sauce keto-friendly?

Some brands include a little sugar. The amount used here is small, but you can omit it or use coconut aminos or tamari for a similar savory boost.

Can I use pre-shredded cheese?

You can, but freshly shredded or sliced Swiss melts smoother. Pre-shredded cheese often contains anti-caking agents that can affect texture.

How do I prevent a watery casserole?

Brown the mushrooms well to evaporate moisture, drain excess fat from the beef, and measure liquids carefully. Let the casserole rest before serving.

Can I cook it entirely on the stovetop?

Yes. Once the cheese is added, cover the skillet and cook on low until the cheese melts. You’ll miss the golden top but save time.

What sides pair well with this?

Try a crisp green salad, roasted broccoli, buttered green beans, or cauliflower mash. Keep sides simple to let the casserole shine.

Wrapping Up

This Keto Mushroom & Swiss Burger Casserole gives you everything you love about a diner classic, made easy at home and tailored for low-carb eating. It’s rich, savory, and dependable—great for meal prep and perfect for family dinners.

Keep the ingredients on hand, and you’ll always have a satisfying option ready to go. Warm, cheesy, and comforting, it’s the kind of dish you’ll crave on repeat.