Cake in the picture has more of chocolate, you can make the layers more prominent by reducing the amount of chocolate. More on this below...
1 cup all purpose flour(maida)
1/2 cup unsalted butter at room temperature
1/2 cup powdered sugar
1/4th cup dark chocolate melted
2 tbsp condensed milk
1 tbsp orange juice
1 tbsp vanilla extract or 5 drops of vanilla essence
pinch of salt
[Vanilla extract - Made out of vanilla fruit.Pure form of vanilla. Vanilla essence - Chemical equivalent of extract.. Its hard to find extract even in cities like Mumbai. You can find it in Godrej Nature's Basket outlets. Essence is easy to find and pretty good replacement for extract. If you are lucky to get extract, add 1 tbsp extract instead of essence in this recipe ]
Now comes the most interesting part ;)
Take another clean dry bowl, add dark chocolate sauce and 1 tbsp milkmaid and mix well! Try to resist the temptation to savour the mixture even before the cake is ready. :-D
Transfer half the cake mixture to this bowl and mix well.
Start by first pouring half of the plain cake mixture, now pour all of the chocolate cake mixture. Pour rest of the plain cake mixture on top.
Preheat microwave at 180 degrees. Once it is done, put the baking tin in microwave (convection mode) and bake at 180 degrees for 30 mins.