Mix flour, baking powder and sugar in a bowl. Whisk egg, milk and oil with a whisk. Add the flour mixture, stir briefly
Wash the apple, grate the flesh roughly from the core and squeeze it
Add apple pulp and raisins to the dough
Grease glasses and fill up to approx. 1/3 with dough. Bake in the preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: level 2) for approx. 35 minutes (test with sticks!)
In the meantime, bring a pot of water to a boil, place 6 suitable lids and preserving rings in it, boil for about 2 minutes, remove from the pot and let it drain on a tea towel
Remove the jars and close them directly with preserving rings, lids and clips. Allow to cool down
Cake can be kept unopened for at least 4 weeks