- 3/4 cup skin-on hazelnuts
- 1 1/4 cups powdered sugar
- 1/3 cup buckwheat flour
- 3/4 teaspoon kosher salt
- 1/2 cup (1 stick) unsalted butter
- 4 large egg whites
- Nonstick vegetable oil spray
- 3 fresh or dried figs, cut lengthwise into 6 wedges (optional)
- Demerara or raw sugar (for sprinkling)
- Preheat oven to 350°F. Toast hazelnuts on a large rimmed baking sheet until skins are slightly darkened and split, 12–15 minutes. Let cool, then bundle in a kitchen towel and rub vigorously to remove skins (there will definitely be some stubborn pieces that refuse to come off—do what you can). Transfer to a food processor and pulse until finely ground. Whisk hazelnuts, powdered sugar, buckwheat flour, and salt in a medium bowl to combine.
- Cook butter in a small saucepan over medium heat until it foams, then browns (be careful not to let it burn), 5–7 minutes. Let cool slightly.
- Whisk egg whites in a medium bowl until foamy (you’re not trying to create volume; you just want to break them up), then whisk into dry ingredients. Whisk in brown butter. Cover and chill batter until firm, at least 2 hours.
- Reheat oven to 350°F. Generously coat six 4-oz. fluted financier molds or a standard 12-cup muffin pan with nonstick spray. Divide batter among molds (use about 1/3 cup batter per mold, or 2 mounded Tbsp. if using a muffin pan). Top with figs (if using) and sprinkle with demerara sugar. Bake until tops are browned and edges are firm, 20–25 minutes. Transfer pans to a wire rack and let financiers cool 10 minutes in pans before turning out onto racks. Let cool completely.
- Batter can be made 2 days ahead. Keep chilled.