Preheat the oven to 375°F (190°C) and position a rack in the center.
Slice the loaf of French bread horizontally into two even halves.
Place the two bread halves, cut sides up, on a baking sheet.
In a small bowl, combine 1 1/4 sticks salted butter, melted; 5 cloves garlic, pureed or very finely chopped; 5 tablespoons bottled Parmesan cheese; and 1 teaspoon finely chopped parsley. Stir until well mixed.
Generously brush the butter–garlic–Parmesan mixture evenly over the cut sides of both bread halves.
Bake in the preheated oven for 15 minutes, or until the garlic–Parmesan topping is golden and slightly crusty.
Remove from the oven, let cool for a few minutes, then slice into pieces with a bread knife and serve warm.