Get the oven hot, about 220.
The spinach leaves should wilt after around seven to ten minutes of cooking in a covered saucepan.
Drain the spinach well by pressing it through a strainer. Give the spinach a little time to chill.
Toss the spinach, ricotta, parmesan, egg, salt, and pepper into a shallow bowl. Be sure to mix everything up well.
With a sharp knife, cut the thawed puff pastry sheet in half lengthwise, creating two long rectangles.
Form a log shape by spreading filling lengthwise and rolling out the crust.
Separate the logs into thirds. Separate the rolls into four equal halves if you want them smaller.
On a baking sheet covered with parchment paper, arrange each roll. Before topping with sesame seeds, brush the rolls with a little beaten egg.
After 20 to 25 minutes in the oven, they should turn a golden brown color.
HINT: I opted with baby spinach. Always take the stems off a bunch of spinach before cooking. Alternately, you may use spinach that is frozen. To prepare spinach from frozen, just follow the same steps.