Preheat the oven to 220 degrees C. Coat a 30-cm pizza pan with cooking spray.
Heat oil in a large non-stick frying pan over medium-high heat. Add mushrooms and cook, stirring or shaking the pan from time to time, until tender and lightly browned, 3 to 4 minutes. Add garlic and cook, stirring, for 30 seconds longer. Remove from the heat and stir in parsley and pepper.
Mix tomato passata sauce and oregano in a small bowl.
If using pizza base dough, on a lightly floured surface, roll dough into a 30-cm circle and transfer to the pizza pan. Otherwise, place purchased pizza base on pizza pan. Spread tomato sauce over the base, leaving a 1-cm border. Sprinkle mozzarella over the sauce. Scatter mushroom mixture over mozzarella. Sprinkle with onion. Top with Parmesan.
Bake until the bottom crust is crisp and golden, 10 to 14 minutes and cheese has melted.
Pizza with broccoli and olives In Step 3, steam 2 cups broccoli florets until crisp-tender, 2 to 3 minutes. In Step 4, mix 1/2 cup prepared tomato passata sauce with 1 teaspoon dried oregano. In Step 5, spread the sauce over the crust. Sprinkle 1 cup shredded reduced-fat mozzarella cheese over the sauce. Scatter the broccoli, 1/2 cup diced red onion and 1/4 cup coarsely chopped, pitted kalamata olives over the top. Spritz the top lightly with olive oil cooking spray. Bake the pizza as directed in Step 6.