Combine the garlic cloves, parsley and olive oil in a small food processor until the garlic breaks down into small pieces. If you're using sliced mozzarella, stack the cheese slices and cut into 1 inch squares.
Heat the butter over medium heat in a small saucepan. When the butter melts, add the chopped garlic to the butter with a pinch of salt and allow the mixture to cook for 2 minutes, stirring as necessary so the garlic does not brown. Remove from the heat.
Position a rack in the centre of the oven and preheat to 375 degrees F. Using a sharp serrated knife, make 1 inch diagonal cuts across the loaf making sure you don't cut the loaf all the way through. Use a spoon to drizzle the garlic butter into the cuts of the bread. Stack 3-4 cheese squares and place them in the cuts. Place the garlic bread on a sheet of foil and fold up the sides. Use a second piece to cover the top. Allow the bread to bake for 10 minutes. Remove the the top piece of foil and allow to bake for another 10 mins or until the cheese is completely melted. Serve warm.