Mix the vegetable oil, milk and egg yolks in a bowl

Add the 1 tablespoon of vanilla essence and 1/4 cup of sugar and mix

Then fold in the shifted flour and corn starch then using a spatula and set aside

In a mixing bowl, pour in the egg whites and set your mixer on medium then high speed and whisk until it reaches stiff peak

Then start adding the other 1/4 cup of sugar little by little while still whisking on high speed

Take quarter of the egg white mix and use a spatula to fold it into the egg yolk mix

Fold it in gently in other not to deflate the egg white mix

Then fold in the rest of the egg white mix in gently

Separate the mixture into different bowls and add individual colors and fold in the colors properly

Pour each colors in different piping bags

Grease a flat baking pan with vegetable shortening and line with baking paper

Starting adding each cake mix color in diagonal lines starting from the corner edge of the pan

Drop pan gently to remove air bubbles and smoothen the mix

Then preheat your oven at 220 degrees and bake at 150degrees for 45-50mins

When ready, gently raise the cake from the pan using the lined baking paper and flip on a cooling rack. Parchment paper side up

Gently peel off the parchment paper

Use a bread knife to slice off the narrow hard 4 edges

Then allow to cool a bit

Flip cake on a new clean kitchen towel and start rolling gently from one edge

Then leave in the towel in that rolled position for 20mins

Prepare your lemon butter cream by mixing the butter, lemon, 1/2 teaspoon of vanilla essence and icing sugar and whisk until lite and fluffy

Gently unroll the cake into a cling film and spread the lemon butter cream on one flat side of the cake

Then gently roll by as previously done but this time in the cling film.

Refrigerate for 2-3 hours or overnight.