Preheat the oven to 400°F (200°C) and place a pizza stone or a baking sheet in the oven if using; otherwise prepare a parchment-lined surface.
On a lightly floured surface, roll the pizza dough into a circle to your desired thickness and transfer it to parchment paper or a pizza peel.
Spread 2 tablespoons Dijon mustard evenly over the dough, leaving a 1-inch border for the crust.
Sprinkle the shredded mozzarella evenly over the mustard layer.
Distribute the diced cooked chicken over the cheese, then evenly scatter the minced garlic, chopped red onion, chopped basil, and diced tomato.
Finish by sprinkling 2 tablespoons freshly grated Parmesan over the top.
Slide the pizza (on parchment) onto the middle or top oven rack and bake for 9 to 13 minutes, until the cheese is melted and the crust is golden.
Remove from the oven, let rest for a few minutes, slice, and serve.
