Welsh Rarebit

2 Tbsp. butter
2 Tbsp. flour
1/4 tsp. mustard
1/2 tsp. salt
few grains cayenne
1 cup thin cream
1 1/2 cups grated cheese
1 egg
toast

Melt butter. Add flour, mustard, salt, and cayenne. Mix well. Add cream slowly and bring to boiling point, stirring constantly. Add cheese and stir until melted. Remove from fire. Beat the egg well and pour hot sauce on it. Mix well. Serve hot on toast.