Preheat oven to 350°F.
Core apples and cut them into quarters.
Mandolin slice the apples.
Add the oat four, almond flour, baking powder and nutritional yeast to a large bowl and stir together.
Add the dates, soy milk and vanilla to a blender and blend until the dates are pulverized.
Pour the soy milk mixture into the flour mixture and stir well.
Add the apple slices to the the batter and massage gently until all of the apple slices are coated with the batter.
Line a 6 1/2 x 2 1/2 inch springform pan with parchment paper.
Layer the apple slices into the pan one layer at a time.
Bake for 1 hour.
Blend the top batter soy milk, dates and vanilla together.
Stir remaining top batter ingredients into the soy milk mixture and pour over the cake making sure that some of the batter creeps down the sides.
Bake for 30 minutes.
Raise the oven temperature to 400°F and bake for another 5 minutes to brown the top.
Let the cake sit for 10 minutes before taking the springform off.
Sprinkle the slivered almonds on top for decoration.
Let the cake rest for at least 20 minutes before cutting.
Keep in the fridge for up to a week in an airtight container.