On a sheet of lightly floured parchment paper, roll out puff pastry to 10 x 16 sheet. Transfer dough on the parchment paper to a large, rimmed baking sheet. Use the tip of a knife to mark a 1 inch border around all four sides of rolled pastry, being careful to not cut thru the pastry.
In a small bowl, add ranch seasoning mix to the cream cheese with chives. Stir until well blended. Use a knife to evenly spread the cream cheese mixture over the dough to the marked border edges.
Scatter shredded chicken evenly over the cream cheese mixture, all the way to the marked border edges. Fill in space between chicken with bacon pieces. Scatter green onions over the top. In a small bowl, whisk egg until yolk and whites are combined. Use a pastry brush to brush egg wash along marked border dough.
Transfer pan to preheated oven and bake for 25 - 30 minutes, until pastry is browned and dough is cooked thru.
Remove from oven and cool 5 minutes on pan set on wire rack. Garnish with additional green onion slices, cut and serve warm.