Place an oven rack 8 inches away from the broiler. Preheat oven broiler to high.
Make Garlic Parmesan Pizza Sauce: Melt butter in a skillet. Saute garlic for 1 minute. Whisk flour into garlic butter. Splash and whisk in a bit of milkat a time until combined over medium heat. Drop in handfuls of Parmesan, whisking until integrated. Season with black pepper and kosher salt.
Spread half the garlicky white sauce on each naan bread. Scatter 1/4 of the fig slices and bacon on top of each pizza. Sprinkle on 1/4 of the mozzarella. Use a pizza peel to transfer naan pizza to the oven. Broil the pizza directly on the oven rack for 3 minutes or until golden on top. Set aside to cool for a few minutes before slicing. Sprinkle on red chile pepper flakes if desired. Broil remaining pizzas.