Preheat the oven to 375 degrees F. Line a baking sheet with parchment paper. Set aside.
Roll the pizza dough into a rectangle about 10 inches x 18 inches. Brush the dough all over with the beaten egg, reserving some egg for later.
Top the pizza dough with sliced meatballs, spinach, mozzarella, Parmesan, and sprinkle 1 teaspoon of Italian seasoning all over the top.
Starting on the long side, roll up the dough like a log and pinch all seams together to seal. Place the bread seam side down on the prepared baking sheet, and brush the outside with the remaining beaten egg.
Bake for 30 minutes or until golden brown on the outside. Remove from the oven and let rest for 5 minutes before cutting into slices and serving with marinara sauce for dipping.
Notes
I use this homemade meatball recipe to make this meatball bread. I usually make a big batch and then freeze the extras for later. You can absolutely use your favorite brand of frozen (and thawed) meatballs or your own homemade recipe for Italian-style meatballs or turkey meatballs if you prefer.