Preheat oven to 200°C (approximately 390°F).
Soak raisins in rum. Peel apples, quarter, remove cores and cut into small cubes. Mix immediately with lemon juice. Mix sugar with butter in a pan and caramelize. Add apples with well-drained raisins and nuts. Sauté 2-3 minutes, remove from heat and let cool.
Mix quark with cinnamon and vanilla extract until smooth. Spread puff pastry out and sprinkle with quark mixture. Create a 1.5 cm (approximately 5/8 inch) wide border around pastry sheet. Spread apple mixture over quark mixture and fold opposing sides slightly toward the center. Roll up puff pastry into a strudel and place with seam side down on a parchment-lined baking sheet. Mix egg yolk with cream and sprinkle top of pastry with it. Bake in preheated oven for about 40 minutes. Remove and cut into pieces to serve warm or cold.