CAKE LAYERS

1. Preheat oven to 350°F (176°C) and prepare three 8 inch cake pans with non-stick baking spray and parchment paper in the bottom. These cakes can have a tendency to stick to the pans a bit, so I strongly recommend the parchment paper in the bottom.
2. Add the flour, sugar, brown sugar, cinnamon, baking powder and salt to a large mixer bowl and combine. Set aside.
3. Add the milk, vegetable oil, vanilla extract and eggs to a medium sized bowl and combine.
4. Add the wet ingredients to the dry ingredients and beat until well combined.
5. Slowly add the water to the batter and mix on low speed until well combined. Scrape down the sides of the bowl as needed to make sure everything is well combined.
6. Divide the batter evenly between the prepared cake pans and bake for 24-28 minutes, or until a toothpick comes out with a few moist crumbs.
7. Remove the cakes from oven and allow to cool for 2-3 minutes, then remove to a cooling rack to finish cooling. These cakes can have a tendency to stick to the pans a bit so jiggle them a bit to loosen from the sides of the pan before turning the cakes out to cool.

BLUEBERRY FILLING

8. Combine the sugar, cornstarch and water in a medium-sized saucepan over medium heat and stir to combine. Heat until the mixture is wet and the sugar begins to melt.
9. Add the blueberries and stir to coat with the sugar mixture.
10. Continue to cook until the blueberries start to soften and let out juice.
11. Remove from heat when blueberries are a bit juicy and the juice has begun to thicken. Pour the mixture into another bowl and refrigerate until cool.

BLUEBERRY FROSTING

12. When everything has cooled, make the frosting. Combine the butter and shortening in a large mixer bowl until smooth.
13. Add about half of the powdered sugar and mix until well combined.
14. Add about half of the blueberry puree and mix until well combined and smooth.
15. Add the remaining powdered sugar and mix until combined.
16. Add the remaining blueberry puree and cinnamon and mix until well combined and smooth.

CRUMBLE

17. Combine the flour, sugar, brown sugar and butter in a medium-sized bowl and use a fork to press the butter into the dry ingredients until it all forms a crumbly mixture.
18. Add the oatmeal and use the fork to press it into the crumbly mixture.
19. Sprinkle the mixture over a lined cookie sheet and bake at 350°F (176°C) for about 5-8 minutes, until the crumble pieces starts to brown around the edges. Remove and set aside to cool.

ASSEMBLY

20. To assemble the cake, use a large serrated knife to remove the domes from the top of the cakes.
21. Place the first layer of cake on a serving plate or a cardboard cake round. Pipe a dam of frosting around the outside of the cake. I use Ateco tip 808 for the dam so that it’s tall.
22. Spread half of the blueberry filling evenly on top of the cake layer, inside the dam.
23. Add some additional blueberry frosting to the top of the blueberry filling and spread into an even layer.
24. Add the second layer of cake and repeat the filling layer with the remaining blueberry filling and additional blueberry frosting.
25. Add the final layer of cake on top, then smooth out the frosting around the sides of the cake.
26. Frost the outside of the cake. Feel free to use my tutorial for frosting a smooth cake.
27. Finish off the cake by pressing the crumble into the sides of the cake, then top with some swirls of frosting, fresh blueberries and additional crumble.
28. Refrigerate cake until ready to serve. Cake is best for 2-3 days.