Makes about 3 dozen
1 cup water
4 tablespoons (1/2 stick) unsalted butter
1/2 teaspoon salt
1/4 teaspoon cayenne pepper
1/4 teaspoon nutmeg
1 cup bread flour
3 eggs
6 ounces grated Gruyère cheese
Kosher salt
Preheat an oven to 425°F.
In a medium saucepan over medium-high heat, combine the water, butter, salt, cayenne and nutmeg and bring to a boil. When the butter has melted and the water is bubbling, remove the pan from the heat, immediately add the flour all at once and beat to blend thoroughly.
Return the pan to medium heat and beat for 1 to 2 minutes, until the mixture gathers into a ball and a film begins to form on the bottom of the pan. (This is to evaporate all the excess moisture.)
Transfer the hot mixture to the bowl of an electric mixer fitted with the paddle attachment. Beat the mixture at medium speed to cool slightly, about one minute. Add the eggs one at a time, beating thoroughly after each addition. Add the cheese, mixing until combined.
Use a small ice cream scoop to portion the mixture onto a parchment-lined, rimmed baking sheet, leaving 1 1/2 inches between scoops. Sprinkle with kosher salt. Bake about 20 minutes, until the puffs are golden brown, crisp to the touch and lift off the parchment. Serve warm.