1 1/2 c. med. Bechamel or Veloute Sauce
1/4 to 1/2 c. grated Gruyere, Swiss or sharp Cheddar cheese
1/4 c. grated Parmesan cheese
1 1/2 tsp. Dijon mustard
3/4 tsp. dry mustard
2 egg yolks, beaten

Place Bechamel or Veloute Sauce in small heavy bottomed saucepan over low heat. Stir in cheeses and mustards. Add small amount of hot sauce to egg yolks, beating constantly. Return yolk mixture to sauce and blend thoroughly with whisk. Over low heat, bring sauce just to boiling point. Makes about 2 cups.