Using the paddle attachment on the mixer, soften the almond paste by adding the egg yolks 1 at a time to avoid lumps. Incorporate the sugar, then the whole eggs, 1 at a time. Mix in the vanilla, salt, and lemon zest. Beat the batter until it is light and fluffy, approximately 5 minutes. Stir in the cake flour.
Spread the batter evenly over a sheet of baking pap