Preheat the oven to 180°C (375°F)
Mix the granulated sugar and cinnamon together. Set aside.
Roll out the puff pastry into a long rectangle. You'll need long strips. It should be about 3mm (1/6 inch) thick.
Cut long strips, about 2.5cm wide (1 inch), then cut four squares, large enough to cover the bottom of the apple.
Toss the apples in the cinnamon sugar, then place them on the squares of puff pastry.
Pull the edges of the square up against the apple. Then with the strip of puff pastry, start wrapping the apple from the bottom up, holding the corners of the bottom piece in place. Let a small hole where the core of the apple was.
Place in the fridge to set up for about 15 minutes.
Mix the egg yolk with a splash of cream and a pinch of salt & sugar to make your egg wash.
Remove the apples from the fridge and transfer to your baking pan. Pipe the salted caramel into the center of the apple.
Brush the puff pastry with the egg wash and sprinkle each apple generously with cane sugar.
Bake for 45 minutes or until the puff pastry is golden brown and a knife can be slid into the apples (through the hole in the top).
Let cool for 15 minutes then serve with vanilla ice cream or extra caramel! Enjoy!