For the crumble, melt the fat and knead with the flour, sugar, egg yolk and cocoa to make crumbs.
Sift the flour onto a work surface. Make a well. Sprinkle sugar in this well and add the egg. Put the butter in flakes on top. Quickly work the dough ingredients into a smooth dough with floured hands. Wrap in foil and let rest in the refrigerator for an hour.
Roll out the dough thinly on a floured work surface and cut out the cookies, place on a baking sheet lined with baking paper. Put the raspberry jam on the biscuits and sprinkle with crumble.