Preheat your oven to 200℃ (400℉)
Peel and halve your apples, set them aside.
From your sheet of puff pastry cut out a circle one inch larger than your pan.
Add the sugar and water to an oven safe pan and melt them over medium heat. Be careful not to burn your sugar! It should have a light auburn color.
Add the butter in small cubes and mix well with a silicone whisk. Remove from heat, add the cinnamon and mix again.
Place your apple halves cut side up in the caramel.
Place your puff pastry disk on top of your apple halves, careful to not burn yourself on the hot pan. With a silicone spatula, tuck the edges of the crust under the apples.
Bake at 200℃ (400℉) for 30-35 minutes until the puff pastry is golden brown and baked through.
Let the tart rest for 5-10 minutes and flip on a large serving platter, being careful to not burn yourself with the hot caramel sauce.
Rest the pie a little more so that the puff pastry can soak in the caramel.
Serve as is or with vanilla ice cream and enjoy!