Italian Walnut Cake, known as "torta di noci," is a classic three-ingredient cake that originated in southern Italy. You can toast the walnuts before grinding them for extra flavor.
Preheat oven to 350 degrees. Grease and line a 9-inch springform pan with parchment paper; set aside.
Pour the walnuts into a food processor fitted with the blade attachment. Pulse until the walnuts are finely diced and resemble a coarse crumb; set aside.
In a bowl, combine the egg whites and half of the sugar. Use an electric mixer to beat the eggs until they are light, foamy, and have doubled in size; about two minutes on high. Set aside.
In a separate large bowl, combine the egg yolks and the remaining sugar. Use the same electric mixer to mix the eggs until they are pale in color and doubled in size; about 2 minutes. Add in the zest, if using. Pour in the crushed walnuts and use a spoon to mix together. Add in the egg whites and use a rubber spatula to mix altogether.
Pour the Italian walnut cake batter into the prepared springform pan. Place on the center rack in the preheated oven and bake for about 30-35 minutes, or until a toothpick inserted in the center of the cake comes out clean. Let the cake cool on a wire rack for 10 minutes before removing the collar. Once cooled completely, dust with powdered sugar, slice, and serve.
Notes
To toast the walnuts, spread them out in a single layer on a baking sheet. Bake in a 350 degree oven for 10 minutes. Cool completely before grinding in food processor.
Adding the lemon or orange zest is completely optional and will add another level of flavor to the cake.
Italian Walnut Cake is a cake that is great to make ahead and tastes even better the next day.
Store leftover cake in an airtight container in the refrigerator for up to a week. You can also freeze for up to a month.