Preheat the Oven
Preheat your oven to 350°F (175°C). Grease your 9-inch round cake pan with butter or non-stick spray, and lightly dust it with flour to prevent sticking.
Prepare the Apples
Peel, core, and slice the apples thinly. Toss them in a little lemon juice to prevent browning. Set aside.
Cream Butter and Sugar
In a large mixing bowl, cream the softened butter and granulated sugar together until light and fluffy. This process usually takes about 2-3 minutes.
Add Eggs and Vanilla
Add the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract until combined.
Combine Dry Ingredients
In a separate bowl, whisk together the almond flour (or all-purpose flour), baking powder, and salt. Gradually add the dry ingredients to the wet mixture, stirring until just combined. Avoid over-mixing.
Fold in the Apples
Gently fold in the sliced apples, ensuring they are evenly distributed throughout the batter.
Pour the Batter into the Pan
Pour the batter into the prepared cake pan, smoothing the top with a spatula. Sprinkle sliced almonds on top for added texture and flavor.
Bake
Bake in the preheated oven for about 40-45 minutes, or until a toothpick inserted into the center comes out clean. The cake should be golden brown and spring back when lightly touched.
Cool and Serve
Once baked, let the cake cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely. Dust with powdered sugar before serving for an elegant finish.