Brown Butter Tiger Nut Genoise

Directions

1. Position a rack in the lower third of the oven and preheat the oven to 350°F. Line the bottom of the pan with parchment paper, but do not grease the sides of the pan.
2. Heat the butter in a small pot until melted and bubbling; turn the heat off under the pot (or set aside if the burner is electric)—put it back on the heat as soon as you start to whip the eggs. Set a 4 to 5 cup bowl (preferably stainless steel) ready near the stove as well—the bowl must be big enough to allow you to fold butter and some batter together later.
3. Combine the sugar, eggs, vanilla, and salt in the bowl of the stand mixer and beat on high speed, about 3 minutes, or until the mixture is pale and has increased in volume: you should see well defined-tracks as the whisk spins but when the whisk is lifted the mixture should flow and sink into the surface of the remaining eggs rather quickly—don’t continue beating all the way to the ribbon stage. You aren’t looking for a mixture so fluffy that it falls back in a thick fluffy rope that dissolves slowly on the surface of the remaining eggs!
4. While the eggs are beating, continue to cook the butter, swirling the pot, it until it is golden brown and the milk particles suspended in it are reddish brown. Immediately pour the butter into the reserved bowl to stop it from cooking further. (It should remain very hot until you need it.)
5. When the egg mixture is ready, remove the bowl from the mixer. Sift one-third of the flour over the eggs. Fold with a large rubber spatula until the flour is almost blended into the batter. Repeat with half of the remaining flour. Repeat with the rest of the flour and any bits of flour that did not pass though the strainer, and the nuts (if using). Fold until blended. Scrape about 1/4 of the batter to the hot browned butter. Fold until the butter is completely blended into the batter. Scrape the buttery batter over the remaining batter, and fold just until blended. Scrape the batter into the pan.
6. Bake 30 to 35 minutes until the cake is golden brown, and springs back when lightly pressed with a finger. Set the pan on a rack. While the cake is still hot, ease a small thin knife or spatula around the inside of the pan, pressing against the sides of the pan to avoid tearing the cake.
7. At your convenience (the cake can be warm or completely cool), invert the pan to remove the cake and peel off the parchment liner. Turn the cake right side up. (The cake should be completely cool before storing.) The cake may be wrapped airtight and stored at room temperature for 2 days, or frozen up to 3 months.