In a large bowl, combine the flour, instant yeast, granulated sugar, vanilla sugar, and a pinch of salt. Whisk them together until evenly mixed.

Introduce the quark, egg, and melted butter into the dry mixture. Use a wooden spoon or spatula to mix until a dough forms. It should be slightly sticky.

Knead the dough on a lightly floured surface for about 5 to 8 minutes until it becomes smooth and elastic. If it feels too sticky, add a bit more flour.

Place the dough in a greased bowl, cover it, and let it rise in a warm spot for about 1 hour, or until it has doubled in size.

Once risen, punch down the dough and divide it into small pieces, rolling them into balls about 1 to 2 inches in diameter.

Heat the oil in a deep pot or fryer to 350°F (175°C). Carefully drop the balls into the hot oil, frying for 3 to 4 minutes, turning for even browning.

Transfer the cooked Quarkbällchen to paper towels to drain excess oil and roll them in a mixture of cinnamon and sugar while still warm.