1Heat oven to 425°F. Lightly spray cookie sheet with cooking spray.
2In medium bowl, stir together Bisquick mix, cheese, sugar, Italian seasoning and red pepper. Add 1/3 cup of the mayonnaise and the milk, stirring with fork until moistened. On lightly floured surface, knead dough 5 or 6 times. Pat or roll dough to 1/4-inch thickness. Cut with 1 3/4-inch round cutter; place rounds on cookie sheet.
3Bake 8 to 10 minutes or until golden brown. Cool slightly. Spread biscuits with half of remaining 1/3 cup mayonnaise; top each biscuit with tomato slice. Spread tomato slices with remaining mayonnaise; sprinkle evenly with bacon and onions.