Cut pepperoni slices in half, and set aside.
Cook ground beef, onion, and garlic in a large skillet, stirring until beef crumbles; drain.
Stir in tomato paste and next 3 ingredients; cook, stirring often, 5 minutes or until thickened. Remove from heat; stir in pepperoni and cheeses.
Combine egg and milk, stirring well; set aside.
Unroll pizza crusts; cut each into 4 squares. Spoon 1/3 cup ground beef mixture onto each square, leaving a 1-inch border around edges; brush borders lightly with egg mixture. Fold in half diagonally, and press edges together to seal. Place on lightly greased baking sheets; brush tops of calzones with egg mixture.
Bake at 350° for 15 minutes or until lightly browned.