Sift together flour,soda and baking powder.

Beat together butter and condensed milk.

Beat in milk,sugar,vanilla and vinegar.

Fold in flour mixture.

Put half of the batter in cocoa and leave the remaining white.

Put cocoa mixture in a greased pan.

Cover it with white batter.

Make deep cuts with a knife.

Bake at 200 C for 30 minutes or till done.

Cool,slice and serve.