Brown Butter Cake
Note: This cake, with its subtle toasted nut flavor and moist buttery texture, is one of the few things I can’t resist, especially when it’s still warm from the oven. It’s also delicious made with hazelnuts or almonds in place of the walnuts.
½ lb. (two sticks) unsalted butter, plus more for buttering the pan
4 oz walnuts
¾ cup all-purpose flour
3 cups confectioners' sugar, plus more for dusting
1 cup egg whites (from about 8 large eggs)
In a saucepan, melt the butter over medium heat and continue to cook it until it turns brown and smells quite nutty, being careful not to let it burn, about 10-15 min. Remove it from the heat and let it cool to almost room temperature.
Meanwhile, heat the oven to 350°F. Butter the bottom of a 10-inch round cake pan and line the bottom of the pan with parchment paper. Spread the walnuts out on a baking sheet and toast them in the oven until lightly browned and fragrant, 10-15 min. Let the walnuts cool but leave the oven on.
Place all of the nuts in a food processor and chop them finely, then reserve ¼ of the nuts. Grind the rest of the toasted nuts until finely ground with about a cup of the flour/powder sugar mix.
Sift the flour, confectioners' sugar, and kosher salt together into a large bowl. Add the ground nuts and whisk to combine. Whip the egg whites to soft peak then add and whisk them together well with the dry ingredients. Slowly add the melted butter, whisking constantly until it is completely incorporated, and no butter is floating on top of the mixture.
Pour the batter into the prepared pan and sprinkle the top with the reserved chopped nuts. Bake until the cake feels solid but still gives slightly when touched, 40-45 min. Let the cake cool in the pan for about 10 min before inverting it onto a serving plate. Just before serving, dust the top with some sifted confectioners' sugar.