These soft, light little puffs pack flavor with the classic addition of Gruyere cheese, in this recipe based on a favorite by Dori Greenspan. The perfect, sophisticated bite served with cocktails. Gougeres freeze so well you can keep them on hand and warm them up straight from the freezer at 350 degrees until heated through.
Position two racks in the middle of the oven with two spaces between them. Preheat the oven to 425 degrees. Line two baking sheets with silicone baking mats or parchment paper.
Bring the milk, water, butter, salt and cayenne to a rapid boil in a medium saucepan over high heat. Swiftly add the flour all at once, lower the heat to medium-low, and immediately beat with a wooden spoon. Keep stirring vigorously over the low heat as the dough smooths out and comes together, about a minute.
Off the heat, add the egg about ¼ cup at a time, beating well with the wooden spoon after each addition. The dough will be wet and somewhat separate, but will come together as more egg is added and as you beat it with your spoon. Leave about ¼ cup of egg behind to use as a wash for the gougères. Beat in the grated cheese.
Drop by the tablespoonful onto the baking sheets, about 2 inches apart, or pipe with a piping bag using a ½-inch tip. Smooth the tops of the gougères by brushing a small amount of egg wash over each one lightly.
Place in the oven and reduce the heat to 375 degrees. Bake for 12 minutes without opening the oven. Rotate the pans from front to back and top to bottom, and bake for another 12-15 minutes, until the puffs are deep golden brown. Do not underbake or the puffs will deflate. Serve immediately, or reheat later at 350 degrees.