Creamy Mushroom Keto Casserole

Prep Time: 15 minutes
Cook Time: 25 minutes
Total Time: 40 minutes
Servings: 6
Calories per serving: 485 kcal

This Creamy Mushroom Keto Casserole is the ultimate low-carb comfort food. Rich, earthy mushrooms are smothered in a velvety Parmesan cream sauce, topped with a golden, crispy cheese crust, and baked to bubbly perfection. With only 6g net carbs per serving, it’s hearty enough to be a main course but also shines as a side dish for steak or roasted chicken.

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Recipe Intensity Levels

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Ingredients

For the Casserole:

• 2 tbsp (30g) unsalted butter or ghee

• 1 tbsp (15ml) olive oil

• 24 oz (680g) mixed fresh mushrooms (cremini, white button, or shiitake), sliced

• 3 cloves garlic, minced

• 1 small onion (or ½ large), finely diced (about ½ cup)

• 1 tsp sea salt

• ½ tsp black pepper

• ½ tsp dried thyme (or 1 tsp fresh)

For the Cream Sauce:

• 1 ½ cups (360ml) heavy cream (35% milk fat)

• 4 oz (115g) full-fat cream cheese, softened and cubed

• 1 cup (100g) freshly grated Parmesan cheese, divided

• ¼ cup (60ml) chicken or vegetable broth (low-sodium)

• ¼ tsp xanthan gum (optional, for thicker sauce)

For the Topping:

• 1 cup (120g) shredded mozzarella cheese

• 2 tbsp chopped fresh parsley (for garnish)

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Instructions

Step 1: Preheat & Prep (5 min – Low Intensity)

Preheat your oven to 375°F (190°C). Grease a 9×13-inch (or similar 2.5-quart) casserole dish with butter or non-stick spray.

Step 2: Sauté the Mushrooms (10 min – Medium Intensity)

Place a large skillet over medium-high heat. Add the butter and olive oil.
Once the butter melts and shimmers, add the sliced mushrooms in a single layer (work in batches if needed). Do not stir for the first 2 minutes – this allows them to brown.
Sprinkle with salt and pepper. Cook, stirring occasionally, until mushrooms have released their liquid and turned deep golden brown, about 8–10 minutes.
Why: Browning = flavor. Pale, steamed mushrooms make a bland casserole.

Step 3: Aromatics (2 min – Low Intensity)

Reduce heat to medium. Add the diced onion and cook for 2 minutes until translucent. Add the minced garlic and dried thyme; cook for 30 seconds until fragrant.

Step 4: Make the Cream Sauce (5 min – Low-to-Medium Intensity)

Pour in the heavy cream, chicken broth, and add the cubed cream cheese. Stir constantly with a whisk or wooden spoon.
When the cream cheese has melted (about 2 minutes), add ¾ cup (75g) of the grated Parmesan and the xanthan gum (if using). Continue whisking until the sauce thickens slightly, about 2–3 minutes. It will not be super thick – that’s fine; it will set in the oven.

Step 5: Assemble the Casserole (2 min – Low Intensity)

Remove the skillet from heat. Pour the mushroom-cream mixture into your prepared casserole dish and spread evenly.
Sprinkle the remaining ¼ cup (25g) Parmesan over the top, followed by the shredded mozzarella cheese.

Step 6: Bake (15 min – No Intensity – Just Wait)

Place the casserole in the preheated oven. Bake uncovered for 15 minutes, then switch the oven to broil (high) for 1–2 minutes to brown the cheese topping. Watch carefully – cheese burns fast.

Step 7: Rest & Serve (5 min – Low Intensity)

Remove from oven. Let the casserole rest for 5 minutes – this allows the sauce to set up. Garnish with fresh parsley. Serve warm.

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Nutrition Facts (Per Serving – 1/6 of recipe)

Calculated using standard keto ingredients. Actual values may vary by specific brands.

Keto Macros (Approximate):

• Fat: 76%

• Protein: 12%

• Carbs: 12% (6g net)