Preheat oven to 375°F (190°C)
Mix softened butter, minced garlic, chopped parsley, salt, and black pepper in a bowl until smooth.
Slice the bread loaf lengthwise and place both halves cut-side up on a lined baking sheet.
Spread the garlic butter evenly over both halves using a pastry brush or knife.
(Optional) Sprinkle mozzarella and Parmesan cheese evenly over the bread.
Bake for 12-15 minutes until golden brown. If making cheesy garlic bread, broil for 1-2 minutes until the cheese is bubbly.
Let rest for 2 minutes before slicing and serving.