Cheesy Beef and Mushroom Casserole
Browned beef, a pile of mushrooms, and a mozzarella melt – 35 minutes
This is a skillet supper that finishes in a foil tin. Beef browns first. Then a heap of mushrooms and onions cook down in the same pan until they go deep brown. A splash of broth and a mozzarella lid go on, and the oven does the rest. No tomato sauce. No rice. Just meat, mushrooms, and cheese like the photo.
About 35 minutes. Cook the mushrooms until their water is gone or the tin gets soupy.
Why you’ll love this casserole
- 42g protein per serving – dinner that holds you
- Only 5g net carbs – mushrooms instead of pasta
- About 35 minutes, one skillet plus the oven
- Philly-steak flavor without the roll
- Foil tin for leftovers or one 8-inch dish
- Steam-hot cheese pull, like the photo
Health notes
- High protein: Lean beef plus a mozzarella lid.
- Low carb: Mushrooms and onion, no rice or noodles.
- No tomato: Broth and Worcestershire keep it savory, not red-sauce.
- Four servings: One foil tin split, or one 8-inch pan.
Key element – brown the mushrooms dry
Mushrooms dump water if you crowd them. Cook them after the beef, in the same hot pan, without adding more oil first. Wait until the liquid cooks off and the edges go mahogany. That is how you get the piled, glossy mushrooms in the photo instead of a gray stew.
Ingredients
Skillet
- 1 1/2 lb (680g) lean ground beef (90/10)
- 1 lb (450g) cremini or baby bella mushrooms, sliced
- 1 medium onion, sliced thin
- 2 garlic cloves, minced
- 1/2 cup beef broth
- 1 Tbsp Worcestershire sauce
- 1 tsp Dijon mustard
- 1/2 tsp dried thyme
- 3/4 tsp salt + 1/2 tsp black pepper
- 1 Tbsp butter (if the pan looks dry)
Top
- 1 1/2 cups shredded mozzarella or provolone
- 2 Tbsp grated parmesan (optional)
Swaps
- Turkey: Use ground turkey and add 1 tsp oil so it browns.
- Swiss: Swap mozzarella for Swiss for a diner melt.
- Creamier: Stir 2 oz cream cheese into the hot beef before you fill the tin.
- One-pan: Skip the foil tin. Bake in an oven-safe skillet.
Instructions
| 1 | Heat the oven. Heat oven to 400 F (205 C). Set out a 9-inch foil tin or an 8-inch baking dish. Slice the mushrooms thick so they still show after they shrink. |
| 2 | Brown the beef. In a large skillet over medium-high, cook the beef 6 to 7 minutes until browned. Season with half the salt and pepper. Drain the fat and move the beef to a bowl. |
| 3 | Cook the mushrooms dry. Add onion and mushrooms to the same hot pan. Do not add extra oil yet. Cook 7 to 8 minutes, stirring now and then, until the water is gone and the mushrooms brown. Add butter only if they start to stick. Stir in garlic 30 seconds. |
| 4 | Sauce and fill. Return the beef. Add broth, Worcestershire, Dijon, thyme, and the rest of the salt and pepper. Simmer 2 minutes until it looks glossy, not soupy. Pack into the tin. Pile extra mushrooms on top. Cover with mozzarella and parmesan. |
| 5 | Bake and rest. Bake 16 to 18 minutes until the cheese is melted and bubbling. Rest 5 minutes so the juices settle. Cut into 4. |
Pro tips
- Thick mushroom slices look like the photo. Thin ones vanish.
- If the pan steams instead of sizzles, cook longer. Water is the enemy of brown.
- Drain the beef hard. Grease in a foil tin has nowhere to go.
- Provolone stretches more than cheddar. Mozzarella is the middle ground.
- Leftovers reheat at 350 F for 12 minutes. The microwave softens the melt.
Nutrition
| Nutrient | Per serving (1/4) |
|---|---|
| Calories | 410 |
| Protein | 42g |
| Net carbohydrates | 5g |
| Total carbohydrates | 6g |
| Fiber | 1g |
| Total fat | 24g |
| Sodium | 720mg |
Estimates with 90/10 beef, cremini mushrooms, and part-skim mozzarella. Cheese brand will shift the numbers.
Variations
Philly
Add 1/2 sliced green pepper with the onion and use provolone on top.
Garlic herb
Stir 1 Tbsp chopped parsley and an extra garlic clove into the skillet at the end.
Creamy skillet
Melt 2 oz cream cheese into the hot beef before you fill the tin.
Meal-prep tins
Divide into 4 small foil cups. Bake 14 minutes. Cool, cover, and reheat 12 minutes at 350 F.
Storage
| Method | Time | Notes |
|---|---|---|
| Refrigerator | Up to 4 days | Covered; reheat at 350 F |
| Freezer | Up to 2 months | Wrap the tin; thaw overnight, then reheat 20 minutes |
| Meal prep | Up to 4 days | Keep in the foil tin; it travels well |
FAQ
Test your knowledge
5 quick questions about this casserole
1. Protein per serving?
2. Net carbs per serving?
3. Oven temperature?
4. Why cook the mushrooms after the beef?
5. When are the mushrooms ready?
