Build the pizza: Preheat the oven according to pizza package directions. In a medium bowl, mix together the ricotta cheese with the lemon zest. Dollop the ricotta on the pizza in several little mounds. Scatter the meatballs on top of the pizza and top it with some mozzarella cheese. Place the pizza into the oven and cook according to package.
Garnish the pizza: Remove the pizza from the oven and top with red pepper flakes, parmesan cheese and some arugula. Slice and serve.