Step 1: Preheat the Oven
1. Preheat Oven: Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

Step 2: Prepare the Filling
1. Mix Filling Ingredients: In a large bowl, combine the shredded chicken, chopped bacon, ranch dressing, mozzarella cheese, cheddar cheese, and green onions (if using). Season with salt and pepper to taste. Mix until well combined.

Step 3: Prepare the Dough
1. Roll Out Dough: On a lightly floured surface, roll out the pizza dough into a rectangle (about 12×16 inches). Make sure the dough is even in thickness.

Step 4: Assemble the Stromboli
1. Spread Filling: Spread the chicken and bacon mixture evenly over the dough, leaving a small border around the edges.
2. Roll the Dough: Starting from one long side, carefully roll the dough tightly into a log. Pinch the seams to seal and tuck the ends under to prevent filling from leaking out.
3. Place on Baking Sheet: Transfer the rolled Stromboli to the prepared baking sheet, seam side down.

Step 5: Brush and Bake
1. Egg Wash: Brush the top of the Stromboli with the beaten egg for a golden finish. Optionally, sprinkle with garlic powder or Italian seasoning for extra flavor.
2. Bake: Bake in the preheated oven for 20-25 minutes, or until the dough is golden brown and cooked through.

Step 6: Serve
1. Cool and Slice: Allow the Stromboli to cool for a few minutes before slicing into pieces. Serve warm with additional ranch dressing for dipping if desired.