Preheat the oven to 350°F. Butter and line a 9 - inch springform pan with parchment and butter the parchment.

Combine the flour, almond flour, 1 teaspoon cinnamon, the baking powder, and salt in a small bowl.

In the bowl of an electric mixer fitted with a paddle attachment, cream ¾ cup sugar and the butter until light and fluffy, 2 to 3 minutes.

Add the eggs, one at a time, mixing well after each addition.

Combine the milk and vanilla in a separate small bowl.

Add the flour to the batter in thirds, alternating with the milk and finishing with the flour, mixing to combine after each addition.

Cut two apples into ½ - inch dice. Add to the batter and mix to combine.

Pour the batter into the prepared pan and spread evenly.

Slice the last apple, lengthwise, into ½ - inch - thick pieces. Toss with the remaining 1 tablespoon sugar and remaining 1 teaspoon cinnamon.

Arrange the slices on the top of the cake, gently pressing into the batter.

Bake the cake until a tester comes clean, 40 to 45 minutes.

Cool slightly and serve warm or at room temperature.

Once cooled, the cake may be stored in an airtight container at room temperature for up to 2 days.