Halve the plums or, depending on the size, quarter them and place in four ovenproof molds.
Then mix the flour and sugar in a bowl with a pinch of salt. Add the butter in small pieces and crumble the whole thing into crumble between your hands. Roughly chop the chocolate and mix with the crumble. For the Christmas variant, it can be seasoned with a little cinnamon or gingerbread spice.
Spread the whole thing over the plums and bake at 190 degrees in the preheated oven on the lowest rack for about 25 minutes.
The recipe can actually be realized with all types of fruit (apricots, apples, pears, rhubarb canned fruit is also possible if necessary). A scoop of ice cream or a fruity sorbet goes well with it - but it is also a real treat on its own!