Low-Carb Ground Beef Stroganoff Casserole

Name: Low-Carb Ground Beef Stroganoff Casserole
Prep time: 30 min
Cook time: 40 min
Total time: 1 h 10 min
Cuisine: European, American
Ingredients: 1 1/2 lbs. ground beef; 2 T olive oil; 1 lb. mushrooms, washed, drained dry, and cut into quarters (I used brown Crimini mushrooms); 1 onion, chopped small; 4 cups cauliflower rice (see notes); 1 tsp. steak seasoning; salt and fresh-ground black pepper to taste; 1 cup grated Mozzarella; 1 tsp. Better Than Bouillon Beef Base (or a beef bouillon cube) mixed with 1/4 cup water and then simmered to reduce to 1 tablespoon thick stock; 1 cup sour cream; 1/2 cup mayo; 1 cup grated Mozzarella cheese; 1/4 cup freshly grated Parmesan cheese; 1/2 tsp. steak seasoning