Delicious Cake with Walnuts

Description
In Romanian: Prajitura delicioasa cu nuci

Ingredients

 * 1 lb / 500 g confectioner's sugar
 * 1 lb / 500 g ground walnuts
 * 8 oz / 250 g butter
 * 5 eggs
 * 1 teaspoon baking powder
 * grated peel from 1 lemon
 * butter for the pan

Directions

 * 1) Cream the butter with the sugar and the gradually added yolks.
 * 2) Add lemon peel, baking powder and walnuts, mixing well.
 * 3) Then add the 5 whipped egg whites.
 * 4) Cover the bottom and sides of the pan with buttered paper, pour the batter in and bake at medium heat for 20–25 minutes.
 * 5) Cut in the pan, while still hot, into small squares or rectangles.