½ C butter
1 C flour
1 C grated gruyère
½ C grated parmesan
2 tsp Dijon mustard
1 tsp pepper
Preheat oven to 425°
Heat butter and 1 cup water in saucepan over medium heat until butter is melted and it begins to boil. Reduce heat; add flour and stir vigorously until mixture pulls away from teh sides of pan and forms a ball. Remove from heat.
Add eggs, one at a time, stirring vigorously after each addition until mixture forms a smooth paste (dough will separage at first after each egg is added). Stir in grated cheese, mustard and pepper.
Drop mixture in heaping spoonfulls onto greased baking sheets. Bake 30 minutes or until puffed and brown. Cut slits in sides of puffs; return to oven, lower heat to 350°. Bake an additional 10 minutes.
Makes 40-45 bite-sized appetizers, less if you make them bigger.