Preheat your oven to 400 degrees. Spray a baking sheet with non-stick cooking spray or use a slipmat.
Roll the pizza dough into a 9X13 rectangle. Partially bake the pizza crust for about seven minutes. Remove from the oven and set aside.
Meanwhile, make the white sauce. In a medium sauce over medium heat melt the butter. Next, add the flour and begin to whisk. Keep whisking until a roux forms about a minute. Gradually pour in the milk, keep whisking. Turn the heat to a medium low and keep whisking until slightly thickened about four minutes.
Stir in the garlic powder, Italian seasoning, salt and pepper. Keep whisking.
Remove the saucepan from the heat and stir in the Parmesan cheese. Taste again for seasoning.
Next, take the sauce and spread it on top of the pizza crust leaving a one-inch border all the way around. Top the white sauce with shredded mozzarella and bake the pizza for about 15 to 20 minutes or until golden brown.
Remove from oven and let cool slightly before topping with smoked salmon, red onion slices and arugula. Enjoy!