Preheat oven to 375°F.
Gently mix first 9 ingredients together; set aside. Brush melted butter onto both sides of bread slices and cut them into 4 squares each. Carefully, push each square into a mini-muffin cup, and fill loosely with lamb mixture. Sprinkle with grated Parmesan and bake 12 minutes, until bread is toasted all around and meat is done. Serve hot.
Note: To make ahead, bake and store, tightly covered, in refrigerator or freezer. To serve, reheat in 375°F oven for about 7 minutes.