1 sheet puff pastry,
defrosted according to package directions
2-3 Tbsp flour
1 small jar of Nutella (you'll use half of it)
Sliced fruit: 1 banana, apple, pear, mango, or 4 large strawberries
1 egg beaten with 1 tsp water
Preheat oven to 450°F. Line a rimmed baking sheet with a Silpat (silicone mat) or parchment paper, and set aside.
Unfold the puff pastry. Sprinkle your countertop with flour, and roll out the puff pastry to a square. With a sharp knife, cut the square into 4 equal pieces.
Spread the inside of each piece of pastry with Nutella, making sure to stay 1/2 inch away from the edge all the way around. Layer slices of fruit on one side of the piece, and sprinkle with sea salt. (Don't forget the salt; it brings out the flavors of the fruit.)
With a pastry brush, paint the edge of the pastry with the beaten egg. Fold the top over to meet the bottom, and press to seal. Use the tines of a fork to seal all the way around. Then, paint the top with the egg wash. Poke a hole in the top with a sharp knife, to allow the steam to escape while baking.
Bake for 18-20 minutes, until the pastry is puffed and pleasantly browned. Serve hot or at room temperature.