Begin with the caramel by heating the sugar in a saucepan slowly on low heat. Make sure the sugar is spread evenly across the bottom and is lump-free. Avoid disturbing the sugar until it begins to melt and turn golden brown.
Cook the sugar until the desired shade of golden brown is reached and remove from the heat.
Add the butter, salt, and stir gently without splashing until blended. Add the cream and stir, placing the pan back on low to medium-low heat to combine the ingredients. Once thoroughly mixed, leave the saucepan set to warm.
Pastry:
Preheat the oven to 400° F (200° C). Place either parchment paper or a silicone mat on a cookie sheet to line.
On a lightly floured surface, roll the puff pastry to slightly under the size of your cookie sheet or just under the silicone mat size, approximately 11x15. It doesn’t need to be exact. Place the puff pastry on the lined cookie sheet and refrigerate until needed.
Peel, core, and slice the apples thinly, between 1/16” to 1/8” thick. Remove the puff pastry from the refrigerator. Begin lining the apples around the edge of the pastry, leaving a 1/2” border edge, overlapping the slices. Continue around in one continuous line of rectangles until the center is reached.
Combine the 2 tablespoons of sugar with the cinnamon if using and sprinkle evenly over the apples. Dot the apples with the cubed butter.
Place in the oven and bake for 30 minutes. The apples will look a bit dried and soft plus be lightly browned. If the puff pastry is bubbling up too much, release the air by poking a small hole.
With a pastry brush, very gently brush the apples (so as to not move them) and edges of the puff pastry with the caramel. Place the tart back in the oven for about 5-10 minutes more, until everything has browned nicely and the caramel is bubbling slightly.
Serve immediately or cool to room temperature.
Notes
**Note: Puff pastry typically comes as a package of two. Use one of the two for this recipe.Adapted from Smitten Kitchen.