Mix the flour, baking powder and sugar in a bowl. Make a well and put the yoghurt and butter in it. Stir the mixture very well so that you get a thick mash.
Transfer it to a floured and buttered tray or cake pan. Distribute the sour cherry jam on top. If you don't have sour cherry jam you can use a different type, as long as it's juicy enough.
Bake the cake in a moderate oven until ready. Then take it out and leave it to cool. When serving, you can sprinkle it with powdered sugar.