Preparation

• Preheat your oven to 350°F. Grease well an 8-inch or 9-inch round cake pan, and set it aside.
• In a large bowl, place the diced apples, and toss with the ground cinnamon, nutmeg (if using), and the lemon juice. Set the bowl aside.
• In a separate medium-sized bowl, place the flour, xanthan gum, baking powder, and salt, and whisk to combine well. Set the bowl aside.
• In another separate, large bowl with a hand mixer or the bowl of a stand mixer fitted with the paddle attachment, place the butter and sugar, and beat on medium-high speed until light and fluffy (about 4 minutes). The mixture will lighten in color and the sugar shouldn't be as grainy.
• Add the eggs and vanilla, and beat on medium speed until smooth.
• Add the dry ingredients, and beat until just combined. The batter will be thick, but smooth and fluffy (not stiff).
• Scrape about two-thirds of the cake batter into the large bowl with the apple mixture. Mix to coat all of the apples in the batter. The mixture will be very chunky.
• Transfer the remaining one-third of the cake batter to the prepared cake pan. With a moistened, small offset spatula, spread into an even layer in the bottom of the prepared pan.
• Scrape the chunky apple-packed cake batter into the pan on top of the base layer of batter, and spread again into an even layer with an offset spatula. If you’ve used an 8-inch pan, the pan will be quite full.
• Cover the pan tightly with aluminum foil, and place in the center of the preheated oven. Bake for 20 minutes.
• Remove the pan from the oven and remove the foil cover from the pan. Return the pan to the oven to bake until a toothpick inserted into the center comes out with no more than a few moist crumbs attached (about another 40 minutes, or about 50 minutes for an 8-inch pan).
• Remove the pan from the oven and allow the cake to cool in the pan for 15 to 20 minutes. The cake will begin to shrink away from the sides of the pan a bit.
• Run a thin spatula along the edge of the pan to ensure that the sides aren’t sticking before carefully transferring the cake to a wire rack, top-side up.
• Allow the cake to cool for about another 15 minutes. Using a very sharp knife, slice and serve the cake, ideally while it’s still warm.