Add vinegar in lukewarm milk. Mix well and set aside for 5 minutes to curdle.
Meanwhile sift 3-4 times the dry ingredients - all purpose flour, custard powder, cocoa powder, baking soda and salt.
The dry ingredients are ready. Keep them aside.
The curdled milk is ready.
In a big bowl add oil and sugar.
Mix well till the sugar is dissolved with a hand whisk.
Add the curdled milk and mix well.
Add red colour and vanilla essence. Mix well. The wet ingredients are ready. (You can add more red colour to get more intense red colour).
Gradually add the sifted dry ingredients in batches to the wet ingredients.
Gently mix all the dry ingredients and mix till the entire mixture is lump free.
Pour the batter in the greased and dusted 10 inch circle pan. Tap the pan 2-4 times and then put it the oven to bake in the preheated oven at 180 C for 40 -45 minutes or till done. Insert a toothpick if it cleans out clean then the cupcake are ready or bake till done. Repeat the above procedure again to make the second base. (Or you can double the quantity of batter divide into two pans and bake).
Remove the pan from the oven. Let it cool for 5 minutes. Run a knife on the edges and unmould the cake and let it cool on a wire rack.