For crumbly doughnuts, prepare the short pastry, either cut out slices or squares and bake at about 170 ° C fairly bright.
Mix soft butter and chocolate with sugar, egg and a little vanilla sugar to taste and coat 1 slice at a time with it and place a 2nd one with the underside on top.
Refrigerate, melt butter and chocolate in a water bath, stir until smooth and dip half of the cookies in it.