Preheat oven to 375 F degrees. Line 2 baking sheets with parchment paper.
Using a sharp knife, cut holes in the top of each dinner roll, big enough to stuff a meatball in it.
In a small bowl whisk together the garlic butter ingredients. Using a pastry brush generously brush some of the garlic butter inside the rolls. Place the rolls on the prepared baking sheets and bake for 10 minutes or until they just start to brown and crisp up.
In the meantime, prepare the meatballs. In a large bowl combine all the meatball ingredients together (minus the olive oil) and shape the meat mixture into meatballs, about the size of golf balls. You should get around 24 meatballs.
In a large skillet, add 1 tbsp of the olive oil and fry the meatballs until golden brown all around, should take around 7 minutes. You will need to do this in 2 batches, 12 meatballs at a time, using the remaining olive oil for the second batch.
Spoon about 1 tsp of marinara sauce into each dinner roll, then place a meatball inside each roll. Spoon another tsp or so of marinara sauce over each meatball then sprinkle with 2 cups of mozzarella cheese over each dozen rolls.
Bake for 10 minutes until the cheese melts and is bubbly then garnish rolls with parsley, and red pepper flakes.