Preheat oven to 400F. Arrange racks in top and bottom thirds of oven. Line 2 baking sheets with parchment. Pour 1/2 cup water into a saucepan and set over high. Add butter, sugar and salt. Bring to a boil, stirring occasionally, 1 to 2 min. Then remove from heat. Using a wooden spoon, stir in fl our all at once, beating briskly until the mixture comes away from the sides of pan.
Scrape dough into a medium bowl or the bowl of a stand mixer. Let dough cool about 2 min. Then beat on low speed, adding 1 egg at a time, letting it be combined into the dough before adding the next one. Stir in 1/2 cup cheese, chives and cayenne. Divide dough into 24 mounds, 1 in. apart on sheets. Sprinkle with remaining 1/4 cup cheese.
Bake for 10 min. Rotate and switch sheets, then reduce heat to 350F. Continue baking until tops are golden, 7 to 10 more min. Remove puff s to a cooling rack. Puff s will keep well, frozen in an airtight container, for up to 1 month. Reheat in centre of 400F preheated oven until warm, 5 to 7 min.
Nutrition (per serving)
Prep Tip: Finely grating the cheese gives the best results.