The key is to first cook the apple slices in butter before adding them to the batter. Not only do the apples get infused with buttery flavor, pre-cooking them helps remove moisture, so the cake doesn’t get soggy. Here’s a tip, don’t leave out the zest! The lemon zest, although only a half teaspoon is used, is an essential ingredient—it helps brighten the flavor of the cake. For information on which apple varieties are best for baking, check out our Guide to Apples. Add the apple slices and the remaining butter to a large frying pan and cook on medium low heat, stirring occasionally, until the apples are tender, about 10 minutes. Remove from the heat. Add the 6 Tbsp of melted butter, the vanilla, the granulated sugar, and the lemon zest. Stir in the flour mixture and the apples. Transfer to a wire rack and let cool in the pan for 5 minutes. Invert the cake onto a plate and lift off the pan, then invert the cake again onto the rack and let cool completely.
