Melt the butter and let it cool down. Grate potatoes. Stir eggs and sugar for about 5 minutes until creamy. Stir in quark and vanilla sugar. Mix flour, baking powder and salt and stir in briefly. Knead potatoes, butter and cranberries into the dough. Heat the oil in a large pot to approx. 175 °C.
Cut off the dough with 2 teaspoons and put it immediately into the hot oil. Bake the quark tips in portions for about 5 minutes until golden brown. Turn once in between. Lift out with a skimmer and drain well on kitchen paper. Put the jam into a piping bag with a pastry syringe and squirt some into each finished quark tip. Dust with icing sugar while still warm and serve immediately