01 - Preheat oven to 375°F and line a baking sheet with parchment paper.
02 - Combine ground beef, breadcrumbs, Parmesan, egg, garlic, milk, oregano, basil, salt, and pepper in a large bowl. Mix until just combined.
03 - Form the mixture into 24 small meatballs, approximately 1 inch in diameter.
04 - Arrange meatballs on the prepared baking sheet and bake for 12 to 15 minutes until cooked through.
05 - Lightly grease a mini muffin tin. Flatten each biscuit and press into the muffin cups to form shells.
06 - Place a baked meatball in each dough cup. Top each with 2 teaspoons marinara sauce and a generous sprinkle of mozzarella cheese.
07 - Brush the edges of the dough with melted butter. Bake at 375°F for 10 to 12 minutes until the dough is golden and cheese is melted.
08 - Remove from oven, let cool slightly, and garnish with chopped parsley if desired. Serve warm.