For the crumble, mix all the ingredients together, then set aside.
For the cake, cream the sugar and butter for about 3 minutes until fluffy and pale. Then add in milk, vegetable oil, mix well.
Sift in flour and baking powder, mix until well combined.
Mix blueberries with one tablespoon of flour. Add the blueberries into the batter, mix well. Pour the batter in lined baking tray, then add the crumble on top.
Pop in preheated oven at 180C, bake for about 50-55 minutes or until fully cooked. Enjoy!