Thaw puff pastry according to package directions.
While pastry is thawing, heat oven to 375℉/190℃.
Line 2 sheet pans with parchment paper. Set aside.
Working with one sheet of pastry at a time, unfold dough and smooth seams.
Cut into 6 equal rectangles.
Place rectangles on prepared sheet pan.
Spoon 2 Tablespoons jam in the center of each rectangle.
Spread evenly over dough, leaving a ½-inch border on all 4 sides.
Make egg wash by whisking egg and water together in a small bowl.
Using a small pastry brush, brush egg wash around the edges of the dough.
Unfold second sheet of dough and smooth seams.
Cut into 6 equal rectangles.
Place rectangles, one at a time, on top of filled dough.
Press gently to seal.
Using a fork, press around the seams to seal, being careful not to press all the way through the dough.
Brush tops of dough with egg wash.
Place in the freezer until cold, about 20-30 minutes.
Bake for 25 minutes, or until golden brown and cooked through.