Preheat the oven at 175ºC/350ºF conventional oven and prepare a 20x20 cm /8 x 8 inch baking pan with parchment paper.
Sift together the all-purpose flour, baking powder, baking soda, cinnamon, allspice and salt and set it aside.
180 g all-purpose flour, ½ teaspoon ground cinnamon, ½ teaspoon ground allspice, ¼ teaspoon baking powder, ¼ teaspoon baking soda, ½ teaspoon salt
Add granulated sugar and butter to a large bowl and using a stand mixer, with a paddle attachment, or a hand mixer, mix it together on high speed for 3 minutes.
200 g granulated sugar, 85 g butter
Scrape down the sides of the bowl and add the eggs one at a time into the mixture and on medium speed mix it in until combined.
3 eggs
Continue by adding ½ of the flour mixture and on low speed. Then add the sour cream, oil and vanilla extract and mix it in. Then add the other half of the flour mixture and give it a final mix until just combined. Scape down the sides of the bowl with a rubber spatula to make sure all the ingredients have been incorporated.
65 g vegetable oil, 2 teaspoon vanilla extract, 150 g sour cream
Pour the cake batter into the prepared baking pan. Then gently divide the cinnamon sugar apples first on top of the cake, followed by the crumble.
Bake it for 1 hour and 10-20 minutes.
Let the cake cool on a cooling rack. After 15 minutes, gently remove the cake from the cake tin and let it cool down completely.