Thaw puff pastry sheets if frozen
Chop and cook spinach, then squeeze out excess water
Mix cooked spinach with ricotta cheese and shredded mozzarella cheese
Add 1 egg to the spinach and cheese mixture and combine well
Season with salt and pepper to taste
Spread the spinach and cheese filling on one sheet of puff pastry
Top with the second sheet of puff pastry
Beat the remaining egg and brush as egg wash over the top
Sprinkle sesame seeds on top if desired
Cut into squares
Bake until golden brown