If you're using a baking steel or stone, place it on a rack in the bottom third of the oven. Set the other rack in the center of the oven and preheat the oven to 400°F. Line a large, rimmed baking sheet with foil or parchment paper.
Trim and chop the eggplant, bell pepper, zucchini, onion, and tomato into small (roughly ½-inch) dice; you should have ¾ cup diced eggplant, pepper, zucchini, and tomato and ½ cup onion. Put the vegetables in a large bowl, add the herbes de Provence, salt, a few grinds of black pepper, and the olive oil, and toss well. Spread out the chopped vegetables in a single layer on the prepared baking sheet.
Roast the vegetables for about 25 minutes, stirring occasionally, until they are tender and browned in spots. Remove the pan from the oven and set it aside to cool while you roll out the pizza dough and grate the cheese. (Or roast the veggies ahead of time and store them in the fridge until you're ready to make the pizza. They will last in the fridge for up to 1 week.)
Increase the oven temperature to 500°F (if using a baking sheet) or as high as it will go (if using a baking stone/steel). Let the oven preheat for 15 to 20 minutes. If you’re using a baking stone or steel, switch the oven to Broil on high.
Stretch or roll out your dough to a 12- to 14-inch circle, then transfer it to a baking sheet / pizza pan or a lightly floured pizza peel (if using a baking stone/steel).
Prick the dough all over with a fork and brush the edges lightly with olive oil. Add the sauce and spread it evenly, leaving a ½-inch border all around, then arrange the garlic on top, sprinkle with the gruyere or mozzarella, scatter on the roasted vegetables and olives (if using), and finish with the parmesan.
Transfer the pizza to the oven and bake until the crust is golden around the edges and evenly browned on the bottom and the toppings have browned in spots—8 to 10 minutes on the baking sheet, 6 to 8 minutes on the baking stone/steel. Remove the pizza from the oven.
Drizzle the pizza with a little olive oil, season with a pinch of salt and a grind or two of black pepper, and sprinkle with the chopped oregano and/or basil. Slice and serve.