Preheat your oven to 375°F (190°C).
Slice the loaf of bread in half lengthwise.
In a mixing bowl, combine the softened butter and minced garlic.
Add salt, pepper, and red pepper flakes to the butter mixture.
Spread the garlic butter evenly on both halves of the bread.
Sprinkle the shredded mozzarella and grated Parmesan cheese generously over the buttered bread.
Place the bread halves on a baking sheet, cut side up.
Bake in the preheated oven for 10-15 minutes or until the cheese is bubbly and golden.
Remove from the oven and sprinkle with chopped parsley.
Slice and serve warm.