Seasoned steak, two kinds of cheese and sautéed onions--if those sound like winning ingredients for a sandwich, wait until your family tries them on a pizza!
Heat broiler. Coat broiler pan with nonstick cooking spray.
In nonstick skillet, heat oil over medium heat. Add onions and 1/2 teaspoon steak seasoning. Cook about 10 minutes or until translucent and lightly browned, stirring occasionally.
While onions are cooking, season steaks with remaining 3/4 teaspoon steak seasoning. Broil for 2 minutes per side. Remove from broiler and slice thinly against the grain.
Place pizza crust on the broiler pan and spread with mustard. Sprinkle half of the Cheddar and provolone over the top; top with sliced steak and onions. Sprinkle remaining cheeses over steak. Broil about 1 minute or until cheese melts and steak is heated.
Remove to cutting board and cut into six slices.