2 large eggs, plus one white
1/4 t salt
1/2 c water
2 T butter, cut into pieces
Pinch cayenne pepper
1/2 c flour
4 oz Gruyere cheese, shredded
Put oven rack in upper-middle position and preheat oven to 425 F. Line rimmed baking sheet with silicone baking sheet or parchment.
Beat eggs with salt in a measuring cup (you want a pour spout) until well combined (no salt dregs at bottom). If you have more than 1/2 cup of eggs, discard excess.
Heat water, butter, & cayenne in a small saucepan over medium heat. When it reaches a simmer, reduce heat to low and dump in flour. Cook, stirring constantly with a wooden spoon using a smearing motion until the mixture is very thick and pulls away from the sides of the pan, about 30 seconds. Immediately transfer to a food processor and process for about 5 seconds with the feed tube open to cool slightly. With processor running, gradually add the egg mixture in a steady stream. Scrape down sides of bowl and add Gruyere. Process until paste is very glossy and flecked with cornmeal sized pieces of cheese, 30-40 seconds.
You can now bake immediately or wait up to two hours. To wait, scrape into small bowl and cover with parchment or waxed paper, pressing to surface of dough; store at room temperature.
To bake, scoop dough in 1 level tablespoon-full scoops onto baking sheet. Use a second spoon to scrape dough out of the first. You should have 24 mounds, 1"-1.25" apart. [Mine were a little bigger spoonfuls and made 18... they turned out fine.] Smooth rough mounds with back of oiled spoon or wet fingertip.
Bake until puffed and upper two thirds of puffs are light golden brown (bottom third will be pale), 14-20 minutes. Turn off oven (don't open) and leave puffs until uniformly golden, another 10-15 minutes. Transfer to wire rack and cool 15 minutes. Serve warm.
To serve later, store cooled puffs in sealed container or ziplock at room temp for up to 24 hours or frozen for up to a month. To serve, crisp in 300 F oven for about 7 minutes.
ALTERNATIVE FLAVORS:
cayenne -> 1/2 t smoked paprika
Gruyere -> aged Gouda
