Crustless Pizza

H/T to my dear mother who suggested this.

Ingredients: Whatever you'd put on a pizza. I like supreme-style pizzas, so here goes.

1 lb hamburger or Italian sausage
2 cups diced bell pepper (about 2 large)
1 cup sliced onion (about 1 medium)
1-2 cups sliced mushrooms
1/4 cup kalamata or Spanish olives, sliced
1 package (about 4 oz) sliced pepperoni
1 25-oz jar spaghetti or pizza sauce
12 oz mozzarella cheese, sliced or shredded, divided

Directions:
1. Brown the hamburger or Italian sausage. Drain and rinse and place in large bowl.
2. Using the same pan and adding oil or cooking spray if needed, saute the bell pepper and onion for 3-4 minutes.
3. Add the sliced mushrooms and continue to saute for another 2-3 minutes. Remove pan from heat and add the vegetable mixture to the hamburger in the bowl.
4. Add the olives, pepperoni, spaghetti or pizza sauce, and 2 cups of mozzarella cheese to the bowl and mix well.
5. Preheat oven to 375. Spray a large casserole dish or 13x9 pan with cooking spray. Place the contents of the bowl in the dish or pan and top with remaining 1 cup of mozzarella. Place the dish or pan in the oven and bake for 15-20 minutes or until cheese is melted and bubbly. Serve immediately.