Cut top third off loaf of bread; hollow out enough bread from the bottom to make room for cheese. Cube removed bread; set aside. Using a knife, make 2-in. cuts into loaf around edge of bread at 1-in. intervals. Spread inside of bread with butter.
Combine the chili powder, sugar, garlic powder and mustard; sprinkle 2 teaspoons into loaf. Top with cheese; sprinkle with remaining spice mixture. Replace bread top.
Transfer to an ungreased baking sheet. Bake at 350° for 25-30 minutes or until cheese is melted. Let stand for 10 minutes. Serve with bread cubes.