Sift all the dry ingredients the flour, baking powder, soda and salt. It's best to measure the flour using a kitchen scale in gms instead of a measuring cup as we often tend to take more than required resulting in a dense cake.
Bloom the Cocoa by mixing with hot water, sugar. Sift the Cocoa. Add instant coffee. Mix well. Blooming Cocoa with a hot liquid ahead helps to intensify the chocolate flavor.
Beat the eggs till frothy for 30 secs. Add sugar in small batches mixing well. Beat on high till almost triples, becomes pale white.
Add the oil or melted butter and vanilla essence.
Add the dry ingredients in three batches alternating with the milk ending with the dry ingredients. Fold gently till just incorporated. Do not over mix.
Pour half of this batter into the cocoa mix. Mix till incorporated.
Grease a 7inch baking tin with oil, dust the sides with flour, place a parchment paper at the base.
Pour equal quantities of vanilla & chocolate batters alternately from the center. Make swirls using a toothpick.
BAKE @160C for 60-65 MINS Or Till a toothpick inserted in the center comes clean.
Allow to cool in the tin for 20 mins before demolding. Loosen the sides gently. Then Reverse on to a plate. Cling Wrap airtight refrigerated till you slice it.
After slicing, Microwave for few seconds to get soft texture. Serve it warm.