Pre-heat the oven to 375. Lightly grease 18-24 mini muffin cups. In a large bowl, whisk together the flour, garlic powder and baking powder. Stir in the milk and egg, then add in the mozzarella and pepperoni and mix together. Let stand for 10 minutes.
Briefly 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 pizza puffs with the pizza sauce for dipping.