Preheat the oven to 375ºF. Line a baking sheet with parchment paper.
Divide the dough into 6 equal pieces. Using a rolling pin, roll each piece of dough into a circle, rectangle or square. (And shape works as long as the width is a minimum of 6 inches.)
In a medium bowl, combine the shredded chicken, mini pepperoni, additional toppings, cheese and 1/2 cup of the marinara sauce, stirring until combined. Divide the mixture between each of the pieces of pizza dough, placing it in the center and leaving a 1/2-inch border around the edges.
Whisk together the egg and the milk then brush the two edges of the dough nearest the filling with the egg wash. Fold the unfilled side of the dough over the filling and very firmly pinch the two pieces of dough together. Place each pizza pocket on the prepared baking sheet then brush the tops with the egg wash and sprinkle them with the Parmesan cheese. Cut a small slit in the top of each pizza pocket.
Bake the pizza pockets for about 20 minutes or until the tops are golden and the dough is fully baked. Remove the pizza pockets from the oven, sprinkle them with the pizza seasoning and serve them with the remaining 1/2 cup of marinara sauce for dipping.