Preheat oven to 350 degrees. Line a square, 9x4 glass baking dish with parchment paper. Or, lightly grease with oil.
Apple Crumble
Peel and chop apples.
Combine flour, brown sugar, sugar, salt, and cinnamon in bowl.
Add vanilla to melted butter, then pour into dry mix. Stir together with a fork to keep it crumbly.
Add in chopped apples and toss together. Set aside.
Cake
In a separate bowl, cream together butter and sugar until light and fluffy.
Add egg and mix. Then sour cream and vanilla and mix.
Combine flour, salt, baking soda and baking powder in another bowl. Mix together this dry mix and butter mix until just combined.
Add half of the batter to lined or greased baking dish. This will be a very thin layer.
Spoon half of apple crumble mix over first layer. Using a fork, spread the mix evenly.
Add remaining batter, and top with the rest of the apple crumble, again using a fork to evenly spread this mix over the top.
Bake for 30 to 35 minutes.
Brown Sugar Cream
Whip together cream, brown sugar, salt and cinnamon until soft, but light firm peaks form. Place in fridge until ready to serve. Spoon over warm Apple Cinnamon Crumble Cake and enjoy!
Notes
If preferred, instead of combining the apples and crumb mixture, keep them separate and layer all the apples coated with cinnamon in the middle of the cake and top with just the crumble.