Preheat the oven to 375F and place rack in the center of the oven.
In a food processor or blender, throw in the garlic cloves, parsley, and olive oil and pulse until you get small pieces.
Melt butter over medium heat and add the garlic mix with a pinch of salt. Cook for 2 minutes while stirring. Set aside.
Cut the bread on a diagonal into 1" diamonds without cutting the bread all the way through. Pry the cuts open and use a spoon to drizzle the garlic butter into each cut of the bread. Stuff the bread cuts with cheese. Drizzle any remaining butter over the crust and add a bit of chopped parsley.
Wrap bottom and sides of bread with foil. Cover the top with a second piece of foil and bake for 10 minutes. Take off top foil and bake for 10 minutes, or until the cheese is melted. Serve immediately.
Notes
If you're using sliced mozzarella, stack 2 cheese slices and cut into 1" squares.To make ahead, wrap with foil and place in a plastic bag. Store in fridge overnight. If you plan on freezing to store for longer, wrap with cling wrap as well after the foil. To bake, thaw and follow recipe instructions.