In a large mixing bowl beat the butter and sugar until pale and fluffy. Add the egg yolks, one at a time, fully incorporating each one before adding another. Stir in the almond flour, ground cookies, cornstarch, lemon juice, lemon zest and yeast.
In another bowl, whip the egg whites until creamy and full. Add 1/3 of the whipped egg whites to the batter and stir to incorporate. Fold in the remaining 2/3 of egg whites. Careful not to lose volume in the egg whites.
Spoon the batter into a greased and floured 9-inch cake pan. Bake at 350 degrees for 35 minutes. Test the middle of the cake with a toothpick. Let cool in the pan for 5 minutes and turn out onto a cake plate.
Use additional lemon zest and powdered sugar to top the cake.
Optional topping: 1/2 cup whipped cream combined with a tablespoon of Stonewall Kitchen Lemon Curd. (Available at Sweet Gourmet.)