For the crumble mixture, mix flour with sugar and baking powder.
Add the oil to the flour mixture and knead with your hands. Add the milk and continue to knead quickly until you have a crumbly mixture.
Pour half of the dough into an oiled and floured cake tin and press down with your hands. Spread the chocolate and jam on top. Crumble the remaining crumble mixture over the top to cover the entire chocolate and jam mixture.
Place the cake in the preheated oven and bake for 30°C at 180 degrees.