1. 1. Preheat the Oven and Prepare Baking Sheet: Start by preheating your oven to 375 F (190 C). Line a large baking sheet with parchment paper or a silicone baking mat. This prevents sticking and makes cleanup a breeze.

2. 2. Prepare the Protein Filling: In a medium bowl, combine the shredded cooked chicken, softened cream cheese, finely chopped celery, finely chopped red onion (if using), garlic powder, salt, and pepper. Mix everything thoroughly until all the ingredients are well incorporated and the mixture is uniform.

3. 3. Unroll the Crescent Dough: Carefully unroll the crescent roll dough onto your prepared baking sheet or a lightly floured surface. Separate the dough into the pre-cut triangles. If your dough comes as a single sheet, you can cut it into 8 triangles.

4. 4. Spoon and Spread the Filling: Take a spoonful of the chicken mixture and place it on the wider end of each crescent roll triangle. Don’t overfill, as this can make rolling difficult. Gently spread the filling evenly across the wider part of the dough, leaving a small border around the edges.

5. 5. Roll Them Up: Starting from the wide end, carefully roll each crescent dough triangle towards the narrow tip, enclosing the filling as you go. Once rolled, gently curve the ends inward to form the classic crescent shape.

6. 6. Egg Wash and Topping (Optional): In a small bowl, whisk the large egg. Brush the tops of each rolled crescent with the beaten egg. This egg wash will give them a beautiful golden-brown finish. If desired, sprinkle the sesame seeds over the top of each crescent for added flavor and texture.

7. 7. Bake Until Golden: Place the baking sheet in the preheated oven and bake for 15-20 minutes, or until the crescent rolls are puffed up, golden brown, and cooked through. The filling should be warm and bubbly.

8. 8. Cool Slightly and Serve: Once baked, remove the crescents from the oven and let them cool on the baking sheet for a few minutes before transferring them to a wire rack. They are best served warm but are also delicious at room temperature.