01 - Set oven to 475°F. If using a pizza stone, position it in the oven during preheating.
02 - In a saucepan over medium heat, melt the butter. Add minced garlic and sauté for 1 minute until aromatic.
03 - Pour in heavy cream and bring to a gentle simmer. Add Parmesan, salt, black pepper, and optional nutmeg. Stir constantly until the cheese melts and the sauce is smooth. Remove from heat and let cool slightly.
04 - On a lightly floured surface, stretch or roll out the pizza dough into a 12-inch circle. Transfer to a parchment-lined baking sheet or a floured pizza peel if using a stone.
05 - Spread 1/2 to 3/4 cup of Alfredo sauce evenly over the dough, leaving a 1-inch border around the edge.
06 - Distribute cooked chicken over the sauce. Top with shredded mozzarella, then sprinkle with additional Parmesan and red onion if using.
07 - Place in the oven and bake for 12 to 15 minutes, or until the crust is golden and cheese is bubbling and browned in spots.
08 - Remove from oven. Garnish with fresh parsley if desired. Slice and serve hot.