Piedmont Hazelnut Torte

From the garden

• 2½ cups shelled hazelnuts, toasted and skinned · about 12 oz shelled, from roughly 1.5 pounds in the shell

From the pantry

• 1 cup sugar · plus 1 tablespoon for the top
• ½ cup butter, softened · plus more for the pan
• 4 eggs, separated, at room temperature
• 2 tbsp cornstarch
• 1 tsp baking powder
• 1 tsp vanilla extract
• ½ tsp salt
• ¾ cup heavy cream, softly whipped (optional) · for serving

1. Heat the oven to 350°F. Spread the hazelnuts on a sheet pan and toast 12–15 minutes, until the skins crack and the nuts smell rich and turn golden under the skin. Tip them onto a clean kitchen towel, fold it over, let them steam a minute, then rub hard to flake off most of the papery skins; a few stubborn patches are fine.
2. Cool the nuts completely, then grind them in a food processor with 2 tablespoons of the sugar in short pulses until they look like coarse sand. Stop before they turn to paste. Stir in the cornstarch, baking powder, and salt.
3. Butter a 9-inch springform or cake pan and line the bottom with parchment. Beat the butter with the remaining sugar until pale and fluffy, 2–3 minutes, then beat in the egg yolks one at a time and the vanilla. Stir in the ground hazelnut mixture; the batter will be thick.
4. In a clean bowl, whip the egg whites to soft, drooping peaks. Stir a third of the whites into the batter to loosen it, then fold in the rest gently in two additions, keeping as much air as you can.
5. Scrape into the pan, smooth the top, and sprinkle with the extra tablespoon of sugar for a crackly crust. Bake 35–40 minutes, until the top is deep golden, the edges pull from the pan, and a skewer in the center comes out with moist crumbs but no wet batter.
6. Cool 15 minutes in the pan, then release and cool fully on a rack. Serve in wedges, plain or with softly whipped cream. Like most nut cakes it is better on day two, once the crumb settles.