Ingredients

170 g Nomix gluten-free flour
30 g fine corn flour
70 g powdered sugar (incl. vanilla sugar)
45 g egg (smaller whole)
80 g butter
40 ml(g) milk
1 TBSP cocoa 
ca. 3 g baking powder

For butter creme: béchamel sauce (mash) from 250 ml
milk and 30 g corn starch,100 g butter,
80 g powdered sugar flavoured with plain chocolate and some rum

Quality plain chocolate and some butter or solid plant fat for the chocolate icing

How to prepare 

Knead the dough ingredients well and let stand in cold. Roll the dough flat (about 3 mm) and cut out small squares. Bake at 160 °C for about 12 minutes. 

Glue together using a butter creme prepared in the following way. Beat the butter well with powdered sugar in approximately 1:1 ratio (less sugar if you want the creme less sweet). Rub some mash, (a thick, cooled pudding) made from milk and corn starch, into this substance. Add as much as you please to enjoy the creme.

Fine-tune the taste by adding chocolate softened on a water bath (softened - not hot) and some rum.

Pour the chocolate icing over each brownie and decorate.