These cheesy puffs look fancy, but come together in minutes to make any snack feel like an occasion.
½ cup water
3 tablespoons salted butter, cut into cubes
¼ teaspoon kosher salt
¼ teaspoon black pepper
½ cup (about 2 1/8 ounces) all-purpose flour
2 large eggs
3 ounces Gruyère cheese, grated (about 3/4 cup), divided
1 ¼ teaspoons finely chopped fresh thyme, divided
½ cup crème fraîche
1 ounce smoked salmon, sliced
½ ounce sevruga caviar (1 tablespoon)
½ teaspoon finely grated lemon zest (from 1 lemon)
1 ounce sliced prosciutto
Preheat oven to 400°F. Line a baking sheet with parchment paper or a silicone baking mat.
Heat water, butter, salt, and pepper in a medium saucepan over medium until butter is melted, about 1 minute. Add flour all at once, and stir vigorously using a wooden spoon until mixture dries a bit and pulls away from sides of pan, about 2 minutes. Remove pan from heat. Carefully pour mixture into bowl of a stand mixer fitted with a paddle attachment; beat on low speed until cool and steam is released, about 2 minutes, stopping to scrape down sides of bowl as needed. With mixer running on low speed, add eggs, 1 at a time, beating until fully incorporated, 1 to 2 minutes. (Batter will be lumpy at first but continue beating until batter smooths out.) Stir 1/2 cup of the Gruyère and 1 teaspoon of the thyme into batter.
Transfer batter to a pastry bag fitted with a wide plain tip or large ziplock plastic bag with tip of 1 corner cut off to create a 1-inch hole. Twist top of bag; pipe dough into 1 1/2-inch mounds (slightly smaller than a ping pong ball) on prepared baking sheet, spacing dough evenly apart.
Top each mound evenly with remaining 1/4 cup Gruyère. Bake in preheated oven until golden brown, about 20 minutes. Remove baking sheet from oven, and pierce each gougère in the side using a small knife. Return gougères to oven, and bake at 400°F for 5 minutes. Remove from oven. Let cool on baking sheet for 10 minutes. Spoon crème fraîche evenly onto gougères (about 1 teaspoon each). Top half of gougères evenly with smoked salmon, caviar, and lemon zest; top remaining half of gougères evenly with prosciutto and remaining 1/4 teaspoon thyme.
