Preheat oven to 375F/190C. Spray a large baking dish with non-stick spray.
Heat a little olive oil in another large non-stick pan and start brown the sausage over medium-high heat, turning occasionally to brown on all sides. (If you’re using pre-cooked sausage you can skip this step and just cut sausage before you brown it.)
Remove sausage to the casserole dish. Set aside.
Sauté mushrooms peppers and onions in the reserved drippings of the sausage pan. Add a tablespoon of butter if necessary.
Layer the peppers, onion, and the mushrooms in the baking dish. Sprinkle with desired amount of grated mozzarella.
Bake about 25 minutes, or until all ingredients are sizzling hot and the cheese is melted and nicely browned.
Total carbs: 5gfiber: 1gNet carbs:4gserves 8serving size 6oz