Preheat the oven to 400 degrees F. Line a large baking sheet with foil.
Place the bread halves (sliced side up) onto the lined baking sheet.
In a bowl, stir together the butter, oil, and garlic powder. Spread onto the bread. Sprinkle on the mozzarella and parmesan cheeses.
Bake until the cheese is melted and the bread is starting to brown along the outside, about 12 to 15 minutes. If desired, broil briefly to brown the cheese in spots.
Sprinkle the parsley on top. Let the bread cool for a couple minutes, and then slice and serve.
Notes
If desired, you can use 4 cloves of minced fresh garlic instead of garlic powder.