
Prepare the dough: combine soft butter and powdered sugar in a bowl and beat with a mixer for a few minutes. Add the egg and beat again.

In a separate bowl, mix the flour, cocoa and baking powder, then combine the butter mixture with the dry ingredients and mix well. Cover the dough with cling film and refrigerate for 60 minutes.

Roll the dough into a 3-4 mm thick layer between sheets of baking paper. Cut out circles from it and place on a baking sheet covered with parchment. Place the baking sheet in the refrigerator for 15-20 minutes. Then bake the blanks in a preheated oven for 8 minutes.

Prepare the filling: beat the soft butter for 2 minutes, then add the powdered sugar, vanilla sugar and beat for another 3 minutes.

Spoon the cream onto one Oreo half and cover with the other, pressing lightly. Transfer the cookies to a container, cover with a lid, and refrigerate for 60 minutes.