Make homemade pizza dough as instructed. Let dough rest while preparing the Alfredo sauce. Preheat oven to 450 degrees F. Spray a 12x17-inch sheet pan with non-stick spray. (I use a light colored sheet pan, not dark.) (Lightly dust pan with cornmeal or flour, if desired.) Set aside.
ALFREDO SAUCE: Melt butter with garlic and onion powder in a medium saucepan over medium heat. Whisk in flour and cook for 1 minute whisking constantly. While still whisking, slowly pour in heavy cream. Bring mixture to a small boil stirring constantly. Remove from heat, stir in Parmesan cheese and season with a dash of pepper. Continue to stir until cheese has fully melted.
Press pizza dough out evenly into the prepared sheet pan. Spread HALF the Alfredo sauce evenly onto dough. Spread cooked chicken pieces evenly over the top. Pour the rest of Alfredo sauce over chicken. Sprinkle Mozzarella cheese all over the sauce and chicken then top with chopped bacon.
Bake in preheated oven for 12 to 14 minutes, or until edges of pizza are golden brown. Remove pizza from oven and top with chopped green onion. Let stand 5 to 10 minutes before slicing into squares. Serve and enjoy!