Mix butter, Parmesan cheese, parsley, and garlic powder in a bowl. Arrange Italian bread on a large baking sheet and spread each slice with garlic butter mixture.
Place baking sheet in freezer and freeze until bread solid, about 1 hour.
Transfer bread to a resealable plastic freezer bag until ready to use.
Preheat oven to 425 degrees F (220 degrees C). Arrange desired number of slices, butter-side up, on a baking sheet.
Bake in preheated oven until bread is toasted and butter is melted, 5 to 7 minutes.