Preheat oven to 350F, and lightly grease an 8x8-inch casserole dish with cooking spray.
Heat a large skillet over medium-high heat and add the ground beef, bell pepper, onion and mushrooms.
1 ¼ pound ground beef, 1 bell pepper, 1 yellow onion, 8 ounces white mushrooms
If adding riced cauliflower, pre-cook it by microwaving according to the package directions. (usually about 4-5 minutes on high) Set aside.
10-12 ounces riced cauliflower
Continue cooking the meat and vegetables, stirring and breaking up the meat with your spoon or spatula.
Once the meat is fully browned and the vegetables are soft, remove excess grease by pushing the meat to one side and dabbing a crumpled paper towel in the pan (held by a tongs) to absorb the grease.
Season the mixture with onion powder, garlic powder, salt, black pepper, and Worcestershire sauce. Add the cream cheese and stir until it fully melts. Add the beef broth and cauliflower and mix well.
1 teaspoon garlic powder, 1 teaspoon onion powder, 1 teaspoon salt, ½ teaspoon black pepper, 2 teaspoons Worcestershire sauce, 4 ounces cream cheese, ½ cup beef broth, 10-12 ounces riced cauliflower
Transfer the mixture into the prepared casserole dish. Overlap the slices of provolone cheese to cover.
6 slices provolone cheese
Bake, uncovered, for 15 to 20 minutes. The casserole will be warmed through and the provolone will be melted.