Preheat oven to 375.
First, roll out the pizza dough (approximately the size and shape of a sheet pan).
Next, spread marinara on the pizza dough leaving 1 inch boarder.
Now sprinkle mozzarella cheese all over the pizza dough leaving 1 inch boarder.
Next, place pepperoni all on top of the cheese also leaving a 1 inch boarder.
Roll up into a jelly roll length wise.
Next, brush the top of the Stromboli with egg and sprinkle mozzarella on top.
Finally, seal the edges, place on parchment lined sheet tray, and bake for 20 minutes on the middle rack (or until browned on the top).