Slice bread in half the long way to make a top and bottom. Butter both sides lightly. Then lightly sprinkle garlic salt on both halves. Sprinkle on mozzarella cheese. Cut Brats in half the long-way and place on top of bread with cheese on it. Then top the brats with cheese. Then place top piece of bread. Wrap in aluminum foil.
Bake at 350 degrees F for 30 min or until bread is crunchy and cheese is melted. Slice in to 4 or 6 pieces. Serve hot.