Roll out the puff pastry until about 10 x 11 inches.
Cut the pastry into 20 squares and place on a lined baking sheet.
Cut the Brie into 20 chunks, roughly equal in size. Place one chunk onto each square.
Place a small dollop, about 1/4 teaspoon, onto each brie chunk.
Remove the rosemary leaves and finely mince them. Sprinkle them onto each jam dollop.
Bring the opposite corners of each square together.
Bring together the other two to form a pouch.
Place the pouches into the freezer for 20 minutes to firm up while you preheat your oven to 375 F.
Mix the egg and water together.
Brush the egg wash onto each pouch and sprinkle them with Fleur De Sel.
Bake for 15 minutes until golden.