2 cups plain flour 1/2 cup sugar 1/2 cup butter 1/4 cup dutch process cocoa powder 1 egg 1 tbsp vanilla extract

first cream the butter and sugar until pale then add the egg and vanilla and mix until its light and fluffy, then sift in the flour and coca powder and mix together until it forms a dough, keep kneading until its all combined, (the dough was dark, but it wasn't black like an oreo so i used a little black colouring just to make sure).
because i was using stamps and cutters and wanted them to be sandwiched together they needed to stay the same size, and as this dough is really wet and delicate i rolled it out to some floured parchment paper and used the cutters on it while it was on the paper and removed the excess dough, then i put the paper straight on to the cookie sheet so i didn't have to move them around .
preheat the oven at 180c.
place them in the freezer for 5 minutes, while the oven is heating up, this helps them hold their shape,
then bake for 8 minutes, and then transfer to a wire rack.

for the filling you will need
1 tsp. plus a heaping 1/4 tsp. unflavoured gelatin
2 TBSP. cold water
1/2 c. shortening
1 tsp. vanilla
2 and 1/2 c. powdered sugar

Combine the gelatin and water in a cup. then put the cup into a larger bowl of hot water and leave it until the gelatin has dissolved and is transparent.

Remove the cup from the hot water and let the liquid cool to room temperature, about 5 minutes.
in a mixing bowl, mix the shortening until its fluffy, then add the vanilla and gradually add the icing sugar until it comes together then add the gelatin and use immediately by putting some in the cookie and sandwiching another on top.
(i have also made the filling with no gelatin and just butter and powdered sugar and it worked fine, if you add enough powdered sugar so that you can shape it like fondant)