Modified from Chef Elisabeth Prueitt’s recipe, published in the Tartine cookbook.
1 1/4 cups nonfat milk
10 tablespoons unsalted butter
1 cup all-purpose flour
6 large eggs
3/4 cup grated Gruyere cheese, plus more for garnish
Preheat oven to 350 degrees. Line a baking sheet with parchment paper; set aside.
Place milk, butter, and 1 teaspoon salt in a large heavy-bottomed saucepan over medium heat. Cook until butter has melted and mixture comes to a boil. Add flour; stir constantly until mixture is smooth and begins to pull away from the sides of the pan, about 3 minutes.
Remove from heat and add 5 eggs, one at a time, making sure each is fully incorporated before adding the next. Mixture will be thick, smooth, and shiny. Stir in cheese.
Transfer baking sheet to oven and bake until puffed, golden brown, and light for their size, 20-25 minutes.