Makes 40-50 pc.
1 cup Water
¼ cup (1 stick) Unsalted Butter
1 cup All Purpose Flour
4 Whole Eggs
1 teaspoon Salt
¼ teaspoon Cayenne Pepper
Pinch Nutmeg
½ cup Parmesan Cheese, finely grated, plus more for topping
½ cup Gruyere Cheese, finely grated
1 Egg, beaten
Coarse sea salt, for garnish

1. Preheat oven to 400°F. In a medium saucepan, bring the water and butter to a boil over high heat, stirring to ensure the butter has completely melted. Add the flour, stirring well with a wooden spoon until the flour has absorbed all of the liquid. Reduce the heat to medium and cook the dough, stirring constantly, until it begins to freely pull away from the sides of the pan, about 2 minutes.
2. Remove the pan from the heat and add the eggs one at a time, stirring well until the egg has incorporated (it will look broken for a few minutes, but should come together in a sticky mass). Continue to add the eggs in one at a time, repeating this process. Stir in the salt, cayenne pepper, and nutmeg.
3. Add the parmesan and gruyere cheeses, stirring well to combine the mixture. Add the batter to a piping bag with a ½” wide tip. Chill the batter in the refrigerator until firm.
4. Line two half sheet trays with parchment paper. Pipe 1” round balls of batter onto the sheet trays, spaced a few inches apart. Brush the tops of each gougere with beaten egg. Sprinkle with a pinch of parmesan cheese and a few grains of coarse sea salt. Bake the gougeres until puffed and golden brown, about 20 minutes. Allow to cool to room temperature on the sheet tray.
5. Once cool, using a small paring knife, make a small “x” in the bottom of each gougere. Pipe a small amount of béchamel into each goygere until it is filled, placing the gougere back on the sheet tray cut side up.
6. Reheat the gpugeres in a 400°F oven until hot, about 5 minutes. Serve warm (check temperature of filling before serving to guests)