Heat oven to 400 degrees. Lightly grease 13 X 9 inch baking dish. Spread taco sauce evenly over bottom of greased dish. Separate dough into 10 biscuits; cut each biscuit into 4 pieces. Place biscuit pieces in taco sauce; turn to coat. Sprinkle biscuit with 1/2 of the cheddar cheese, 1/2 of the mozzarella and the olives. Mix gently. Bake at 400 degrees for 15-18 minutes or until bubbly. Meanwhile, in a large skillet, combine ground beef, bell peppers and mushrooms. Cook until beef is browned; drain. Sprinkle remaining 1/2 cup Cheddar cheese and mozzarella over mixture in casserole; top with ground beef mixture. Bake 5-7 minutes more or until mix bubbles vigorously around edges. 8 servings.