To begin, take the pizza dough out of the fridge and let it rest, out of the plastic bag and in a large bowl coated in two tablespoons of olive oil, for at least an hour.
About ten minutes before the dough has finished resting begin to make the béchamel. Add butter to a medium sized pot over medium heat. Let the butter melt and then sprinkle in the flour. Using a wooden spoon, stir for a few minutes until the butter and flour have incorporated. Switching to a whisk, slowly pour in the milk. Continue to whisk until the sauce has thickened, about five minutes. Remove from heat and season with salt, pepper and nutmeg. Set aside.
Pour olive oil onto a 13x18 inch sheet pan and spread it out, covering the whole pan. Place the rested dough in the middle of the pan and, using your finger tips, gently stretch the dough out to meet the sides of the pan. If the dough continues to spring back, let it rest another 15 minutes before stretching again.
Once the dough has been stretched, pour the béchamel over top and spread it out evenly. Scatter pieces of stuffing, diced turkey and roasted squash over the béchamel. Cover with grated mozzarella and place in the oven on the bottom rack and bake for 20-25 minutes.
Remove the pizza from the oven and let it rest for five minutes. Sprinkle the top with fresh arugula and enjoy!