Preheat your oven to 220C and line 2 large baking trays with baking paper. In a small bowl, mix together the quince paste, sultanas, wine, and cinnamon.
Cut an 18cm square from 1 pastry sheet. Set an apple in the middle. Fill with 2 teaspoons quince mixture. Brush the edges with egg. Wrap the pastry around the apple, pinching to seal. Trim excess and create 2 leaves and a rosette. Place on a tray. Brush with egg, top with leaves and rosette, then chill. Repeat with remaining ingredients.
Bake the apples on trays, swapping halfway, until the pastry is golden and the apples are cooked through, about 25-30 minutes. Serve with custard.