For the fruity donuts, peel apples and cut into wide rings, then core with a sharp knife and cut a not-too-small hole in the center of the slices.
Mix cinnamon with sugar in a bowl.
Drain the pineapple slices and toss them in the sugar-cinnamon mixture. Also dip the apple rings in the mixture on both sides.
Cut puff pastry into narrow strips, divide each in half and stretch a little longer. Then wrap each fruit ring with the dough strips and place on a baking sheet lined with parchment paper.
Brush the rings with beaten egg and sprinkle with hail sugar.
Bake the fruity donuts in a preheated oven at 180 °C for about 15 minutes.