Preheat oven to 450F (230F). Rub a large rimless baking sheet with oil.
On a lightly floured work surface, use a rolling pin and your hands to roll and stretch dough into a 15-by-11-inch rectangle. Transfer to prepared sheet.
Spread sauce evenly over dough, leaving a 1-inch border all around. Top with provolone, tomatoes, and if desired, onion; scatter chicken over top. Season with salt and pepper.
Bake until crust is golden, chicken is cooked, and cheese is melted, about 20-30 minutes. Serve immediately.