Recipe Instructions:
3/4 pound (340 grams or about 3 cups) shelled walnuts
4 eggs, separated
1 cup (225 grams) caster sugar (superfine sugar)
Finely grated zest of 1 lemon
Confectioners' sugar for dusting
Pulverize the walnuts in a food processor until you have a coarse meal, the texture of sand.
Prepare a round 9-inch cake pan by greasing and lining it with parchment paper.
Beat the egg yolks with the sugar until pale and creamy. Add the lemon zest and walnut meal and stir to combine. Whisk the egg whites in a separate bowl until they form stiff peaks. Fold the whites bit by bit into the walnut mixture until well combined.
Pour the mixture into the prepared cake pan and bake at 375º F (190º C) for about 50 minutes, or until the top is firm and browned nicely. Let cool completely in the pan before removing. This cake is even better the day after it is made or after it has had some time to settle -- wrap in plastic wrap tightly and let chill in fridge until 1 hour before serving. Dust with confectioners' sugar or do as Ada Boni suggests and fill or cover the cake with a lemon buttercream.
