In a small saucepan, combine beef consomme, Worcestershire sauce, garlic powder, and onion powder; simmer over low heat for 10 minutes to create the au jus.
Spread butter evenly on one side of each bread slice.
Place two bread slices, buttered side down, in a non-stick skillet over medium heat.
Layer one slice of provolone, 4 ounces of roast beef, and a second slice of provolone on each piece of bread in the skillet.
Top with the remaining bread slices, buttered side up.
Grill for 3 to 4 minutes per side until the bread is golden brown and the cheese is completely melted.
Remove from heat and slice each sandwich diagonally.
Pour the hot au jus into small ramekins and serve alongside the sandwiches for dipping.