Preheat the oven to 180℃, line an 8inch baking tin with butter, baking paper and set aside.
In a medium bowl mix all the ingredients for the crumble topping until combined and sticky. Set aside.
In a large bow beat the butter until paler with a whisk or spatula. Add the sugars and beat well until creamed together.
Add the eggs one at a time and beat well. Add the vanilla and beat again.
Mix the flour, baking powder, baking soda, salt in another bowl and add half the mixture into the butter and eggs. Add all the yogurt and mix well.
Add the remaining dry mixture and add the apples. Fold together until combined.
Spoon half the batter into the tin, sprinkle in the cinnamon powder, drizzle over the caramel sauce and swirl with a spoon.
Add the remaining batter on the top, add more caramel and cover the top with the crumble mixture. Use your fingers to read it out evenly.
Bake for 50-55 mins until golden and tooth pick inserted into the center comes out clean.
Let it cool for 10 mins before removing from the tin and leaving to cool at room temperature. Slice while warm and serve with more caramel sauce.