Cut the pastry sheet in 8 pieces the same size.
Peel the apples and slice them. Arrange them all around the pastry sheet (4 slices by piece).
Sprinkle with sugar and cinnamon.
Using a knife, make 3 incisions on each piece of pastry, on the inside.
Fold from the center to the outside.
Brush with egg yolk and bake for 20 minutes at 350°F (180°C)
There you are, your express apple turnovers are ready!