French Dip Sandwiches

1 long loaf French bread
1/2 pound cooked roast beef (from deli or leftovers)
1 package roast beef au jus gravy
4 tablespoons butter
1 teaspoon garlic powder

Cut French bread in half lengthwise. Spread with butter and sprinkle with garlic. Wrap in foil and heat in oven until warm. Mix gravy as directed on package and warm beef in juice. Drain beef from gravy and put on bottom of warm bread. Put top on sandwich and slice. Put gravy into small bowls (one for each person). Dip sandwich in gravy to eat.