Step 1

Finely grind the almonds in a food processor.

Step 2

With an electric mixer, beat the egg yolks with the sugar to a smooth pale cream. Beat in the zests and almond extract. Add the ground almonds and mix very well.

Step 3

With clean beaters, beat the egg whites in a large bowl until stiff peaks form. Fold them into the egg and almond mixture (the mixture is thick, so you will need to fold it quite a bit).

Step 4

Grease an 11-inch springform pan, preferably nonstick, with butter and dust it with flour or spray with cooking spray. Pour in the cake batter, and bake into a preheated 350°F for 40 minutes, or until it feels firm to the touch. Let cool before turning out.

Step 5

Just before serving, dust the top of the cake with confectioners' sugar. Or, if you like, cut a St. James cross out of paper. Place it in the middle of the cake, and dust the cake with confectioners' sugar, then remove the paper.