Preheat oven to 350°F (175°C). Grease a 9-inch cake pan or line with parchment paper.
Cream butter and sugar until light and fluffy. Beat in eggs one at a time, then stir in vanilla extract.
In another bowl, whisk together all-purpose flour, almond flour, baking powder, baking soda, salt, and cinnamon.
Gradually fold dry ingredients into wet mixture. Gently fold in chopped apples.
Pour batter into prepared pan and smooth the top. Sprinkle sliced almonds evenly over the top.
Bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean.
Let cool for 15 minutes in the pan, then transfer to a wire rack. Slice and enjoy warm or at room temperature.