These are apparently the new "in" thing and outselling cupcakes throughout London...so ive tried 3 different recipes changing the flour and this is the closest to the taste and texture..
oven 180 degrees  6/8 mins baking time
125 gr butter
150 gr chocolate and 50gr for coating
225 gr feine sugar
75gr cocoa powder
3 eggs
225gr cakemeel (no other flour will work)
1/2 teaspoon baking powder
makes approx 12/16

Marshmallows or buttercream

Whisk together sugar and eggs till pale in colour
Melt 150gr chocolate and butter in microwave or pan...
When melted add to the whisked mixture whisking all the time till all blended.
Fold gently into the mixture, flour, cocoa and baking powder.
Once all mixed add dessertspoons of mixture (onto a baking tray lined with greasproof paper)
You should get between 24/32. I did 3 lots.

Dont spread the mixture it will spread itself while in the oven.
Once cooled either sandwich together with buttercream or get a large marshmallow and place on the bottom Whoopie and put bak in oven for 2 mins once mallow has gone soft squash the top Whoopie onto and it should ooze out.
Spread 50gr melted Chocolate over the tops and decorate.

The outer should be crispy and the inside should be chewy...