Preheat your oven to 400°F. Line a baking sheet with parchment paper.
Roll out the pastry on a lightly floured surface to form a 14 x 12-inch rectangle. Cut the pastry lengthwise into two long strips.
Spread the pesto over each strip, leaving a one-inch border around the edges to help the pastry stick when folding.
Shape the sausage meat into long logs that fit the length of the pastry strips, placing them on top of the pesto.
Make the egg wash by lightly beating the egg in a small bowl. Brush the edges of the pastry with the egg wash.
Fold the pastry over the sausage filling and press the edges to seal tightly. Crimp the edges with a fork for a decorative touch. Repeat with the second strip of pastry.
Slice each roll into eight bite-sized pieces using a serrated knife, trimming off and discarding the ends.
Brush the tops with more egg wash, sprinkle with sesame seeds, and place them on the prepared baking sheet. Make a small slit in each roll to allow steam to escape and ensure even cooking.
Bake for 20-25 minutes, or until the sausage is fully cooked (internal temperature of 140°F) and the pastry is golden. Turn the baking sheet halfway through for even browning.