Procedure
1) Preheat the oven to 170C / 150C fan.
2) Put all the cake batter ingredients into a bowl and mix well until you get smooth batter.
2) Line a 20x30cm cake tin/baking tray with parchment paper and pour the cake batter into the tin. Spread the rhubarb on top, try to spread it evenly to cover the whole cake. Finally, make the crumble topping by bringing all the ingredients together and running them between your fingers until the mixture resembles crumble like mixture. Sprinkle the crumble topping over the rhubarb layer, making sure it is completely covered.
3) Bake the cake in the preheated oven at 170C / 150C fan for about 30 minutes. Let cool, slice and serve. Enjoy!
