Preheat your oven to 400°F. Halve the bread lengthwise. Prepare a baking sheet by layering it with two slightly overlapping 24-inch pieces of foil.
In a bowl, combine the softened butter, olive oil, minced garlic, salt, and pepper with a fork until well mixed. Spread this mixture generously over the cut sides of the bread, ensuring even coverage to the edges to prevent burning. Wrap the bread in foil, sealing the edges, and place it on the prepared baking sheet. Bake for 10 minutes.
After 10 minutes, remove the bread from the oven, unwrap the foil, and fold it inward. Evenly sprinkle the shredded mozzarella and parmesan cheeses over the bread. Return it to the oven, baking uncovered for an additional 5-6 minutes. For a crispier texture and a more golden finish, broil for the last 1-2 minutes, without moving the oven rack. Once done, sprinkle with fresh parsley, slice, and serve warm.