Method (cake)

1. Preheat your oven to 180ºC fan and line an 8 x 8 inch square cake tin with greaseproof paper. Allow the paper to hang over the tin slightly, this makes it easier to remove the cake when baked.
2. In a bowl, combine the dairy-free milk with the apple cider vinegar and whisk until fully combined. Set aside for 10 minutes to curdle. This creates a vegan buttermilk.
3. In a large mixing bowl, sift the sugar, flour, baking powder, bicarbonate of soda and ube powder. Mix well to combine. Add the oil and ube condensed milk into the ‘buttermilk’ and whisk to combine.
4. Add the wet ingredients into the dry ingredients and mix just to combine.
5. Pour batter into the lined tin and spread out until its flat and even.
6. Place the cake into the middle of the preheated oven and bake for around 25-30 minutes. You will know it is done when you put a knife or skewer down the middle of the cake and it comes out clean and it’s springy to the touch. If batter comes off on the skewer, it needs more time to bake. To prevent burning, top the cake with some greaseproof paper then return back into the oven.
7. Allow the cake to cool in the tin for 10 minutes then carefully transfer onto a cooling rack. Allow to cool fully before frosting. You can even place the cake in a sealed container once cool then frost the day after. It’s a very light sponge so be careful with it when removing from the tin.

Method (buttercream)

1. In a stand mixer with balloon whisk attachment or in a bowl with a hand whisk, whisk on high speed for around 5 minutes / cream the butter until pale and fluffy. 
2. Gradually add in the icing / powdered sugar along with the vanilla and the ube (both powder and condensed milk). Whip until it’s thick and fluffy. If its too thick, add in some more chunks of butter, too soft, add in more icing sugar to get it to the perfect creamy consistency. 
3. Spoon the buttercream on top of the cold cake (make sure its fully cold as any heat from the cake will instantly melt the buttercream). Spread out using an off set spatula or the back of a spoon. Make swirls in the buttercream for decoration.
4. Add some ube condensed milk to the top of the cake (refer to video for example), and swirl around.
5. Lastly, finish with a dusting of ube powder.
6. Slice the cake into squares using a shark knife.
7. Serve and enjoy!