These fluffy-light cheese puffs are dangerously easy to eat. A perfect finger food for entertaining, they could also be called cheese bubbles, because their interiors are filled with air. Not surprisingly, they pair quite well with their bubble-filled liquid counterpart—sparkling wine. Gruyère cheese, made in the French and Swiss Alps, is a semi-hard, aged cheese with a nutty quality. In the absence of Gruyère, other semi-hard cheeses such as Cantal, Asiago or white Cheddar would make delectable substitutes.
1/2 cup unsalted butter
1/2 tsp salt
1 cup all-purpose flour
6 large eggs
1 1/2 cups shredded Gruyère cheese
Preheat the oven to 400°F.
In a medium saucepan over high heat, combine 1 cup water, the butter, and the salt. Bring to a boil and stir until the butter has melted. Reduce the heat to low, add the flour to the pan, and stir constantly with a wooden spoon until a smooth dough ball forms and pulls away cleanly from the sides of the pan, about 1 minute.
Transfer the hot dough to a large bowl. Using an electric mixer, add 5 of the eggs, one at a time, and beating well between each addition. Continue beating until the eggs are fully incorporated into the dough. Add 1 cup of the cheese and beat until well combined.
Line 2 large baking sheets/trays with parchment/baking paper. Using a spoon, place teaspoon-size dollops of dough on the parchment, leaving enough space between the puffs for them to double in size.
In a small bowl, beat the remaining egg with 2 tablespoons water. Gently brush the cheese puffs with the egg wash. Sprinkle the remaining 1/2 cupg cheese evenly over the tops.
Bake until the puffs are lightly golden and have doubled in size, 15–20 minutes. (If you are using 2 racks in the oven to accommodate the 2 baking sheets, switch the top and bottom sheets after 8–10 minutes to ensure even cooking.) When the puffs have doubled in size, open the oven door slightly, reduce the heat to 250°F, and continue baking until the puffs are golden brown and appear full of air, 5–10 minutes longer. Serve warm or at room temperature.