2 teaspoons fresh thyme leaves, plus more for garnish
5 large eggs
Preheat oven to 400 degrees. Line 2 large baking sheets with parchment paper. Set aside. In a large heavy saucepan, bring the butter and 1 cup of water to a bowl. Once the mixture is boiling, remove from heat and add the flour, salt, cayenne, and black pepper. Stir vigorously to blend. Return to medium heat and stir vigorously until mixture forms a ball and a thin, dry film forms on the bottom and sides of the pan, about a minute.
Transfer mixture to a stand mixer with a paddle attachment. Add 1 1/4 cups Gruyere, Asiago, and 2 teaspoons thyme. Beat on low speed to blend. Add 4 eggs, one at a time, letting each one fully incorporate before the next is added. Scrape down the sides of the bowl as needed. Spoon the dough into a pastry bag fitted with a 1/2” tip or a plastic bag with 1/2” cut diagonally from 1 corner.
Pipe dough onto prepared baking sheets in 1”-1 1/4” rounds, spacing 1” apart. Whisk remaining egg with 1 tablespoon water in a bowl to make an egg wash. Brush the egg lightly over the rounds. Sprinkle the remaining 1/4 cup of Gruyere over the gougéres. Garnish each with a few thyme leaves. Bake gougéres until puffed and golden brown and centers are cooked through but still moist, 20-25 minutes. Let cool slightly and serve. NOTE: Can be made 1 month ahead. Let cool completely. Store airtight in the freezer. Rewarm in a 325-degree oven until hot, 10-15 minutes. (Adapted from “The New Formal”. bon appetit, October 2011: 82)