Preheat your oven to 425F and line one large baking sheet with parchment paper.
Cut your pastry sheets into four, 6x10-inch rectangles. Place three back in the refrigerator while you shape.
Spray your work surface with the oil spray, top it with one piece of the puff pastry and stay the top of the dough and your rolling pin.
Roll the pastry into a 12x16-inch very thin rectangle.
Top the long side of the dough with the spinach filling, about one inch away from the edge of the dough. The filling should be about one inch thick and about 1/2-inch tall.
Top the filling with the extra one inch dough then roll it into a log.
Starting from one end, fold the log into itself towards the other end so you'll have a swirl.
Gently lift the pastry and place it over the prepared baking sheet.
Repeat with the rest of the dough pieces.
Brush the pan pastries with the egg wash and sprinkle with the sesame seeds.
Bake for 15 minutes then reduce the oven temperature to 380F and bake for an extra 30-25 minutes. Until the pastries are dark and golden brown at the top and the bottom.
Remove from the oven and serve.