Defrost the pastry sheets. Caramelise the sugar in an ovenproof pan (approx. 20 cm Ø) until golden yellow. Let it cool down in the pan. Spread butter in flakes on top
Peel and quarter the apples and remove the core. Cut apples into slices. Sprinkle with lemon juice and schnapps. Place apple slices fan-shaped on the caramel
Place the dough sheets next to each other with a slight overlap lengthwise and press on the middle seam. Roll out slightly if necessary. Cut out a circle (approx. 20 cm)
Cover apples completely with puff pastry. Bake in the preheated oven (electric cooker: 225 °C/circulating air: 200 °C/gas: level 4) for approx. 35 minutes. Carefully turn the tart over. Cut into 4 pieces. Sprinkle with pistachios. Whipped cream tastes good with it
Simply cut out small motifs from the leftover dough and bake with it. Serve with it or nibble extra