Preheat oven to 350° F.  Line the bottom of a 9” round cake pan with parchment and spray with non-stick cooking spray.

For the Crumb Topping:

1. Combine flour, cornstarch, brown sugar, salt and cinnamon in a medium bowl and mix well.

2. Add vanilla extract to melted butter and stir to combine.

3. Add vanilla and butter to dry ingredients and mix well with a spatula or spoon until dry flour is visible and large and small clumps are forming. Cover with plastic wrap and place in freezer for 30 minutes.

For the Cake:

1. While the crumb topping chills: Spread the diced apples in a single layer on a parchment lined baking sheet and bake at 350º F for 20 minutes. Remove from the oven and set aside to cool for at least 10 minutes.

2. While the apples are baking: Combine cake flour, baking soda and baking powder in a medium bowl and whisk thoroughly to combine. (Ready a sifter to sift these ingredients into wet ingredients when ready.)

3. Melt butter in 1 cup microwave safe measuring cup. Whisk in canola oil and set aside.

4. Combine milk, vinegar and vanilla in a small bowl or 1 cup measuring cup and stir to combine. Set aside.

5. Once apples have cooled for 10 minutes: Combine the sugar, salt and egg in a medium to large bowl. Immediately beat with a hand held mixer on medium speed for 3 minutes until the mixture is thick, fluffy and pale. When the beater is stopped and lifted the mixture should ribbon off the beater and leave a trail for a second before disappearing into the rest of the mixture.

6. Turn the beater to medium low and slowly drizzle in butter and canola oil while continuing to mix until the mixture is nicely emulsified. Set aside handheld mixer.

7. Switching to a hand whisk and mix the milk mixture into the egg mixture until just combined. The mixture will loosen but will still be very foamy.

8. Quickly sift in prepared flour mixture and gently, but deftly stir in by hand with a whisk until just combined and no dry flour streaks or large lumps remain. Do not over mix! This should be the consistency of pancake batter with small lumps visible.

9. Pour batter into the prepared cake pan and run a butter knife back and forth through the batter once to make sure there are no large bubbles.

10. Sprinkle the cake batter evenly with the cooled diced apples. Try to keep the apples in a single layer and do not press the apples down into the batter.

11. Sprinkle the top of the apple topped batter evenly with the chilled crumb topping. Use your hands to break up any really large clumps as you distribute the crumb topping. Make sure you get the crumb topping all the way to the edges of the pan.

12. Transfer cake to the center of your preheated oven and bake for 45-50 minutes, rotating the cake halfway through baking. The cake is done when the crumb topping has started to brown, a knife inserted into the center comes out clean or it reaches and internal temperature of 195°-200º F in the center when tested with an instant read thermometer.

13. Remove the cake from the oven and place on a cooling rack in the pan to cool for 10 minutes.

14. Cover the top of the cake pan with an inverted dinner plate and turn cake out onto the plate. Peel the parchment paper off the bottom of cake. Place a cooling rack over the bottom of the cake and carefully flip the cake back to crumb side up on the cooling rack. Let cool completely on cooling rack before cutting and serving.