Preheat: First preheat oven to 350°F (175°C) and lightly butter or oil an 8-inch cake pan.
Mix Dry Ingredients: In a large mixing bowl, whisk together almond flour, coconut flour, baking powder, baking soda, cinnamon and nutmeg.
Mix Together Wet ingredients: In another bowl, mix eggs with sweetener, almond milk, melted butter and vanilla.
Add: Add the dry mixture to the wet just a little at a time while folding it together (do so slowly and gently) until they are fully combined into a batter. Substitute finely chopped zucchini for your apple.
Bake: Pour the batter into the prepared cake pan and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Cool & Serve: Allow the keto apple dessert to cool for 15 minutes, then cut it and serve.