Preheat oven to 350 degrees Fahrenheit.

Whisk together butter, Parmesan, grated garlic, garlic powder, parsley, red pepper flakes, and salt in a small mixing bowl until well combined; divide into 2 servings.

Separate roll tops from bottoms, keeping all 12 of each connected as one piece, place bottom piece on small baking sheet, and brush with 1 serving prepared garlic butter.

Layer bottom piece with four slices of provolone, followed by the 12 meatballs. Spoon marinara sauce over meatballs and top with remaining 4 slices of provolone.

Place the top piece of rolls over the top layer of provolone.

Using a pastry brush, brush other serving of garlic butter over top.

Cover tightly with foil and bake for 20 minutes, then remove foil and bake an additional 10 minutes, until the meatballs’ internal temperature reaches 140 degrees Fahrenheit, as per a meat thermometer.

Finish with freshly grated Parmesan and serve!