Gat d'Ametlla

Preparation Preheat the oven to 400F. Butter an 11-inch round cake pan with 2-inch sides and then dust it with flour, shaking out any excess. In a large bowl, combine the egg yolks and sugar an whisk together until smooth and foamy. Add the lemon zest, cinnamon, and vanilla, if using, and mix well. Add the ground almonds a little at a time, mixing well after each addition to incorporate fully. Using a whisk or a handheld mixer, beat the egg whites until they form soft peaks. Scoop about one-third of the whites onto the egg yolk mixture and, using a rubber spatula, fold them in to lighten the mixture. Then add the remaining whites and fold them in gently but thoroughly, deflating the batter as little as possible. Transfer the batter to the prepared pan. Bake the cake for about 30 minutes, or until a knife inserted into the center comes out clean. Remove from the oven and, holding the cake pan 6 inches above a countertop, drop the pan onto the counter. This simple dropping action shocks the cake, making it easier to remove from the pan. Transfer the cake to a wire rack and let cool in the pan until warm. Run a knife around the inside of the pan to loosen the cake sides and then invert the cacke onto the rack and lift off the pan. Place the cake upright on a serving plate. Serve warm or at room temperature with ice cream, if desired.