Melt butter on a very low heat in a thick bottom pan. Remove from the heat and let it cool to room temperature.

Sift all purpose flour, cocoa powder, baking powder, baking soda and a pinch of salt for three time. (Sifting the dry ingredients helps in uniform mixing of the dry ingredients and helps in getting aeration .

After the butter comes to room temperature, add the condense milk to it.

Beat it well with a hand whisk for 3-4 minutes till the mixture becomes white, light and fluffy.

Now add the dry ingredients gradually in two batches.

Mix them well with light hands.

Add the remaining dry ingredients.

Mix well.

Now add the cola drink to it.

Give it a quick mix.

Pour the mixture into a greased and dusted tin.

Bake for 40-45 minutes at 150 C or till done. The time varies from oven to oven. Just check by inserting the toothpick. If it comes our clean the cake is done or bake for further 5 -10 minutes. Cool for 5 minutes and unmould the cake on a wire rack. Serve it warm or cold. Use it as a base for making different kinds of cakes such as black forest or any theme cake.

I have made both in square and round tin. So have shared the pics of both.