INGREDIENTS
4
Eggs, large
1 tsp
Dijon mustard
1/2 tsp
Mustard, dry
3 tbsp
All-purpose flour
1/4 tsp
Cayenne pepper
1/4 tsp
Cream of tartar
1 1/4 tsp
Kosher salt
3 tbsp
Butter, unsalted
6 oz
Gruyere cheese
1 1/4 cups
Heavy cream
3/8 cup
Parmigiano-reggiano cheese
2 tbsp
Sour cream
3 tbsp
Sherry, dry