1 cup water
2 tablespoons butter
1/2 teaspoon salt
1/8 teaspoon cayenne pepper
1 cup all-purpose flour
1-1/4 cups shredded Gruyere or Swiss cheese
1 tablespoon Dijon mustard
1/4 cup grated Parmesan cheese
In a large saucepan, bring the water, butter, salt and cayenne to a boil. Add flour all at once and stir until a smooth ball forms. Remove from the heat; let stand for 5 minutes. Add eggs, one at a time, beating well after each addition. Continue beating until mixture is smooth and shiny. Stir in Gruyere and mustard.
Drop by rounded teaspoonfuls 2 in. apart onto greased baking sheets. Sprinkle with Parmesan cheese. Bake at 425° for 15-20 minutes or until golden brown. Serve warm or cold. Yield: 4 dozen.
Recipe found here: Cheese Puffs