Preheat oven to 400 degrees F.
In a large bowl, combine all meatball ingredients except olive oil. Mix until just combined. Roll into 12 small meatballs, slightly smaller than a golf ball.
Heat olive oil in a skillet over medium-high heat. Sear meatballs 1 to 2 minutes per side until browned. Transfer to a baking sheet and bake 10 to 12 minutes until internal temperature reaches 160 degrees F. Reduce oven to 350 degrees F.
Using a small knife or spoon, cut a round pocket into the top of each roll without cutting all the way through. Place hollowed rolls on a foil-lined baking sheet.
Add a small pinch of shredded cheese into the bottom of each roll pocket. Place one meatball into each roll. Spoon a small amount of marinara over each meatball. Top with remaining shredded cheese.
In a small bowl, mix all garlic butter ingredients. Brush generously over the tops and edges of the rolls.
Bake at 350 degrees F for 12 to 15 minutes until cheese is melted and bubbling and rolls are golden brown.
Sprinkle with chopped parsley. Serve warm with extra marinara, garlic aioli, or pesto for dipping.