Preheat the oven to 375 degrees F (190 degrees C).

Cut bread into 1-inch thick slices, without cutting all the way through the loaf. Combine butter, Parmesan cheese, garlic powder, and parsley in a small bowl; spread between bread slices and over top of loaf. Wrap loaf in aluminum foil, leaving top partially uncovered.

Bake in the preheated oven until butter melts and bread toasts, 15 to 20 minutes.