Divide rolls into 2 sections of 6 each. Half sections horizontally. Spread bottom halves with a thick layer of Bolognese sauce or thick marinara. Sprinkle with half of cheese.
Place pepperoni between paper towels and microwave for 20 seconds to render fat.
Divide slices between the 2 roll bottom sections, placing 3-4 slices of pepperoni on each individual roll bottom. Sprinkle with remaining cheese and replace top sections. Carefully cut out individual rolls along bakery lines. Place rolls close together in a foil lined baking pan.
Melt butter and season with salt, pepper and garlic powder to taste. Brush roll tops with butter and sprinkle with parsley. Cover and refrigerate until baking if desired.
Bake covered for 15 minutes, then uncover and bake another 15-20 minutes until heated through and golden.
Serve warm. Reheat leftover rolls for 20 seconds each in microwave