If using Publix Pizza dough, let it sit out for at least an hour to make it easy to work with. If using homemade pizza dough or Pillsbury pizza dough, roll out onto pizza pan.
Heat oven to 400 degrees and bake pizza crust for 5 minutes (bake it for 8-9 minutes if using Publix dough - it takes longer to cook.)
Meanwhile, saute garlic in butter on stove top for 1-2 minutes over medium heat.
Add in milk and half & half and whisk together, then reduce heat to medium-low.
Sift flour using whisk, then slowly pour into milk mixture whisking constantly to keep it from getting lumpy.
Add pepper, oregano, parsley and garlic salt and continue to whisk well until it thickens, for just 1-2 minutes.
Turn off heat and add Parmesan cheese.
Stir until cheese is melted.
Remove pizza dough from oven.
Top with sauce, then add cooked chicken.
Add cheese, onions and mushrooms.
Bake at 400 for another 5-6 minutes if using Pillsbury dough, 9-10 minutes if you're using Publix dough.
Set your oven to broil for 1-3 minutes, or until lightly browned.
Enjoy!