Cut the apples, and cut them in big chunks. In a bowl, toss them and add some sugar (1/4 cup). Let to rest for around 15 to 30 minutes while we prepare the caramel.
Pre-heat the oven at 205ºC.
In a pot, melt the butter and gently add the remaining sugar. Stir continuously.
The sugar will start bubbling at some point, continue stirring then add the milk. Continue stirring until the caramel reaches a much harder, texture, kinda like a spreadable.
Pour the caramel into an already greased tart pan, and then place the apples on top, arranging them as you want (we tried to do a pattern but then we were too excited and just made them all fit in).
Roll out the puff pastry and cover your pan. Tuck in the pastry inside the pan and then make a hole with the help of a knife in the middle of the pastry.
Place inside a previously heated oven (205ºC) for around 30 to 40 minutes. Take out of the oven when the pastry is cooked and looks brownish.
To plate it, place a large enough plate on top. Hold the pan and plate together with a hand towel and then flip it carefully. It's okay if some caramel spills, there will plenty more left. Lift the pan and ta-da. It's there!
Enjoy it with some vanilla ice-cream or just plain. You choose!