- unsalted butter, for greasing pan
- 4 eggs, yolks and whites separated
- ½ cup plus 2 tablespoons superfine sugar
- 8 ounces crème fraîche
- zest of 1 large unwaxed lemon
- 1 cup chestnut flour, sifted
- 2 teaspoons baking powder
- powdered sugar, for dusting
Preheat oven to 350°. Butter the base of an 8-inch springform pan, line with parchment paper, and butter the parchment.
Beat egg yolks with sugar in a large bowl until light and creamy, about 2 minutes. Stir in crème fraîche and lemon zest. Add chestnut flour and baking powder.
In a separate bowl, whisk egg whites until stiff, then fold into the flour/crème fraîche mixture using the whisk blades.
Pour into pan and bake 35–40 minutes, until cake feels firm to the touch. A toothpick inserted should come out clean. Cool in pan for 5 minutes, then turn out onto a wire rack and cool completely. Dust with powdered sugar and serve.