Preheat oven to 400°F. Slice off both ends of loaf; cut remaining bread into 10 slices to make 5 sandwiches. In small bowl, combine butter and garlic powder. Spread butter on one side of each bread slice; place 5 slices, buttered-side down, on foil-lined rimmed baking sheet. Top each with a slice of ham or salami, cheese and remaining bread, buttered-side up. Bake for 5 minutes.
Remove; set oven to broil. Return sheet to oven and broil 2-3 minutes per side or until bread is lightly browned.