Preheat oven to 350°F (175°C). Grease a 9-inch round cake pan.
In a large bowl, mix almond flour, coconut flour, coconut sugar, baking powder, baking soda, salt, and cinnamon.
In another bowl, whisk eggs, melted coconut oil, almond milk, and vanilla extract.
Combine wet and dry ingredients, then fold in diced apples.
Pour batter into the prepared pan and smooth the top.
Bake for 45 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.