Step 1
Preheat the oven to 350 degrees F (375 degrees C). Lightly butter an 8-inch baking pan.
Step 2
Arrange enough apple wedges to form a single layer over the bottom and sides of the prepared pan.
Step 3
Heat a saucepan over medium heat. Add almonds; cook and stir until toasted 4 to 5 minutes. Remove from heat.
Step 4
Beat 3 1/2 tablespoons butter white sugar and 1/4 cup brown sugar together in a bowl using an electric mixer until smooth. Add egg applesauce and honey; beat until smooth. Stir buttermilk almond extract and vanilla extract into the batter.
Step 5
Combine flour baking soda and 1/2 teaspoon salt in a bowl; stir mixture into the batter. Mix until well combined. Fold in 3/4 of the remaining apple wedges. Pour batter into the prepared pan. Top with 2 tablespoons toasted almonds.
Step 6
Bake the preheated oven for 35 minutes.
Step 7
Heat oats in a saucepan over medium heat; cook and stir until slightly toasted about 5 minutes.
Step 8
Stir 3 tablespoons butter and 1/3 cup brown sugar together in a bowl until combined. Add remaining almond slices oats milk and 1 pinch salt.
Step 9
Top the cake with remaining apple slices and oat mixture. Return to the oven and continue baking until a toothpick inserted into the center of the cake comes out clean 10 to 15 minutes more. Let cool to room temperature at least 25 minutes.