Preheat your oven to 375°F (190°C).
Slice the French bread in half lengthwise to create two long pieces. Place them cut-side up on a baking sheet.
In a mixing bowl, combine the softened butter, minced garlic, salt, pepper, and dried parsley (if using). Mix well until the ingredients are combined.
Spread the garlic butter mixture evenly on the cut sides of the bread.
Evenly distribute the mozzarella and cheddar cheese over the buttered bread, making sure to cover it completely.
Bake in the preheated oven for about 20 minutes, or until the cheese is bubbly and golden.
Remove from the oven and let it cool for a minute. Cut into pieces and serve warm.
For an extra crispy finish, broil the bread for an additional 2-3 minutes after baking, but keep a close eye to avoid burning.