Warm the butter in the water bath until it is almost liquid. Add icing sugar and mix well with the mixer. Add the 3 yolks one at a time. After another short mixing, stir in the flour and cocoa powder.
Pour the creamy mass into a piping bag and sprinkle small dots or sticks on a baking sheet lined with baking paper.
Bake in the oven at 170 ° C for about 7 to 10 minutes. The baking time is different for each oven. The biscuits are ready when they can be easily removed from the baking sheet.
Let the biscuits cool down and then glue 2 halves together with apricot jam. The biscuits can be sprinkled with chocolate, or half covered with chocolate, as desired.