Variations: Substitute orange zest for lemon for a warmer flavor, or use hazelnut flour for a different nutty depth. Add a splash of vanilla extract or a pinch of cinnamon or cardamom for subtle nuance. Serve with whipped cream, fresh berries, or a drizzle of honey or amaretto. Cake can be stored at room temp for 2 days, refrigerated up to 5 days, or frozen for longer storage.