Preheat the oven at 180° C/360° F.
Grease a Ø23cm round springform cake tin.
Beat the sugar, eggs and vanilla for at least 4-5 minutes until it is pale and fluffy.
Add milk, lemon juice and vegetable oil to the mixture and mix for another minute until combined.
Gradually add the flour and baking powder to the wet mixture, and fold the mixture with a spatula or hand whisk. As of this stage, do not use an electric whisker as it will cause the cake to be denser and less spongy.
Pour the cake batter into the pan and evenly distribute the blueberries on top of the batter.
Cover the cake with the crumble and cook it for 50 minutes or until the crumble looks golden brown and fully cooked.
If you are not sure if the batter is cooked or not, use a toothpick to check if batter is cooked. Do not open the oven before 30-35 minutes as it will affect the rising of the cake.
Let the cake cool down for at least 45 minutes before slicing. Do not cover with a cloth at this stage.