Sausage and Mushroom Low-Carb Breakfast Casserole
- Prep
- 15 min
- Cook
- 30 min
- Yield
- 6 servings
- Level
- medium
- Cuisine
- American
Protein-packed breakfast casserole layering caramelized mushrooms, wilted spinach, and sliced Polish sausage bound with a creamy egg custard and melted mozzarella. Savory, satisfying, and keto-friendly, this one-pan dish works for weekend brunch, meal prep breakfasts, or lazy morning entertaining. The combination of sausage fat and heavy cream creates a rich, tender crumb without grains or starches.
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Method
9 steps- 1
Preheat oven to 375F.
- 2
Heat butter and olive oil in a large skillet over medium heat. Saute sliced mushrooms until soft, then add spinach and cook until wilted.
- 3
Transfer vegetables to a baking dish.
- 4
Thinly slice the sausage links and cook in the same skillet for about five minutes.
- 5
Add cooked sausage to the baking dish with vegetables.
- 6
Whisk eggs with heavy cream, half the mozzarella, salt, and pepper.
- 7
Pour egg mixture over sausage and vegetables.
- 8
Cover and bake for 15 minutes.
- 9
Sprinkle remaining mozzarella over top and bake uncovered for 15 minutes more until set.
Tips
Cook mushrooms in batches if crowded in the skillet to achieve browning instead of steaming.
Divide the mozzarella: reserve half for the egg mixture and half for topping to ensure even melting throughout.
Good to Know
Cover and refrigerate up to 4 days. Reheat covered at 350F until warmed through, about 10-12 minutes.
Assemble the casserole through the egg pour step, cover, and refrigerate overnight. Bake directly from cold, adding 5-10 minutes to baking time.
Serve warm from the skillet or dish. Pairs well with hot sauce, avocado, or a simple green salad.
Common Mistakes
Do not skip sauteing mushrooms until soft to avoid watery, rubbery texture from excess moisture.
Divide cheese properly to avoid a dry top layer; reserve half for mixing into custard.
Substitutions
Dairy-Free Swaps
General Alternatives
FAQ
Can I use frozen spinach instead of fresh?
Yes, thaw and squeeze out all excess moisture first. Frozen spinach releases more liquid during cooking, which will dilute the egg custard if not drained well.
What if I don't have heavy cream?
Substitute with half-and-half or whole milk for a lighter version, though the custard will be less rich. Use the same quantity.
How long can I keep leftovers?
Refrigerate covered up to 4 days. Reheat in a 350F oven until warmed through. Not recommended for freezing due to texture breakdown of eggs.