Melt butter in a saucepan over moderate heat, blend in flour, and slowly stir in milk. Heat, stirring until thickened. Add cheese and stir until melted. Beat yolks lightly, blend in a little hot sauce, and return to pan. Heat and stir for 1-2 minutes over lowest heat. Take pan off heat and mix in salt and pepper. Lay a piece of wax paper on surface of sauce and cool to room temperature. Meanwhile, preheat oven to 350 F. Beat egg whites until stiff but not dry, stir about 1/4 cup into sauce, then fold in remaining whites. Spoon into an ungreased 5-cup souffle dish and bake uncovered, 35-40 minutes until puffy and browned. Serve at once.