Preheat the oven to 180°C.
In a bowl, stir the milk, cider vinegar, vanilla extract and light olive oil.
In a separate bowl, add the flour, sugar, baking powder, ground almonds, and lemon zest. Stir to combine.
Now add the liquid to the dry mix. Stir thoroughly to combine.
Pour the mixture into a lined, loose-bottomed cake tin.
Slice the rhubarb in half lengthways and then into approx 2-inch slices.
Add them to the top of the cake mix and press them down a little.
Sprinkle with sugar.
Now place into the oven to bake for roughly 40-45 minutes. Check it’s done by inserting a toothpick into the middle of the cake – if it comes out clean, it’s cooked.
Once baked, remove from the oven and allow to cool completely.
Keep cake in the fridge and enjoy.