In the top of a double boiler melt 1 tablespoon butter. Add 1 cup beer. Cook over hot (not boiling) water until beer is warm. Stir in 1 pound grated Cheddar cheese until it melts. Stir in 1/2 teaspoon dry mustard, 1/2 teaspoon paprika, 1 teaspoon Worcestershire sauce and salt & pepper to taste.