Prep Time: 10 minutes
Cook Time: 30 minutes
Ready In: 1 hour 10 minutes
Make Sure You Have: peeler, large sauté pan, and parchment paper
1. Preheat the oven to 375ºF.
2. Peel the apples and cut them into slices, removing any bits of the core. Place them in a large sauté pan and add butter, lemon juice, sugar, and kosher salt.
3. Cook over medium-high heat initially, then reduce heat to medium. Cook until the apples are soft all the way through while still maintaining their shape. Once the apples are done let them cool to room temperature. If desired, place the apples in the refrigerator to allow them to cool more quickly. You can prepare your apple mixture a few hours or even a few days ahead of time and store in the refrigerator until you are ready to assemble your tartlets.
4. Cut each puff pastry sheet into four even squares. Place a generous amount of apples in the middle of each square, bring the four corners of the pastry to the center, and pinch them together to close the tops. Place tartlets on a baking sheet and refrigerate for 30 minutes.
5. Place in the oven at 375ºF and bake for approximately 25 minutes. Top with crème fraiche and serve warm! (Tartlets may be made ahead and reheated in the oven before serving.)