Pre-heat the oven to 375°. Grease a 24-cup mini-muffin pan. In a large bowl, whisk together the flour, garlic powder and baking powder; whisk in the milk and egg. Stir in the mozzarella, sausage and pepperoni; let stand for 10 minutes. Stir the batter and divide among the mini-muffin cups. Bake until puffed and golden, 20 to 25 minutes. Meanwhile, microwave the pizza sauce until warmed through. Serve the puffs with the pizza sauce for dipping.