Preheat your oven to 425°F (220°C).
In a mixing bowl, combine the softened butter, garlic powder, dried parsley, salt, and black pepper. Mix until well blended.
Spread the garlic butter mixture evenly on one side of each slice of bread.
Place the slices butter-side up on a baking sheet.
In a separate bowl, mix the shredded mozzarella and grated Parmesan cheese together.
Evenly sprinkle the cheese mixture over the buttered sides of the bread.
Bake in the preheated oven for 10-12 minutes, or until the cheese is melted and bubbly, and the edges of the bread are golden brown.
Remove from the oven and let cool for a couple of minutes before slicing and serving.