Preheat oven to 300 degrees F. Cut bread into 1-inch cubes (you should have about 3-1/2 cups); set aside. In a small saucepan, melt butter; transfer to a bowl. Stir in Parmesan cheese and garlic. Add bread cubes, stirring until cubes are coated with butter mixture. Spread bread cubes in a single layer in a shallow baking pan or on a baking sheet.
Bake for 10 minutes; stir. Bake about 10 minutes more or until bread cubes are crisp and golden. Cool completely. Transfer croutons to canister; cover.