Preheat the oven to 400, line baking sheet with parchment paper and lightly grease it.
Combine flour, sugar, salt and cinnamon in a bowl of an electric mixer. Chop cold butter into small pieces and add it to flour.
Start mixing on slow until it looks like coarse crumbs. Add cold water and keep mixing until dough comes together. Transfer onto a work surface and knead a few times. Cover in saran wrap and pop in the refrigerator for about 30 minutes.
Peel, core and slice apples thin.
Roll out the dough into a circle, about 1/8 of an inch thick. Carefully roll it into a loose tube, place it on the greased parchment paper and carefully unroll it back out.
Spread caramel all over the dough, leaving a little space uncovered around the edges.
Lay out apple slices to form a spiral pattern in the center, leaving about an inch and a half of dough to fold.
Drizzle a little more caramel over apples.
Fold edges of the dough up, over the apples, all around the circle.
Whisk egg white with a splash of water and brush the outer edges of the dough. (You won't use all of the egg-wash.)
Bake for 35-40 minutes, until apples are cooked and crust is golden.