Preheat the oven to 400°F and line baking sheets with parchment paper.
Cut the butter into small pieces and put in a saucepan with milk, water, and kosher salt. Bring to a boil.
½ cup milk, ½ cup water, ½ cup unsalted butter, 1 teaspoon kosher salt
Add all of the flour at once, reduce heat, and stir with a wooden spoon. After about 2 minutes, the dough will start drying out and pulling away from the pan. That’s precisely what you want. This will make your gougères crispy on the outside.
1 cup all purpose flour
Scrape the dough into a mixing bowl and let cool for a couple of minutes.
Add eggs one at a time and beat them into the dough.
4 large eggs, at room temperature
Once the dough is mixed well, add cheese, Dijon mustard, black pepper, nutmeg, and cayenne pepper, and mix again.
2 cups coarsely grated Gruyère cheese, 2 teaspoons Dijon mustard, Pinch of black pepper, Pinch of nutmeg, Pinch of cayenne pepper
Transfer the dough into a pastry bag with a ½” round tip and pipe tablespoon mounds two inches apart on the baking sheets. You can also use a spoon or a cookie scoop instead.
Bake for about 25 minutes until they’re nicely puffed up and golden brown. Gougères Gruyère are best served warm. Enjoy!