Heat olive oil in a large pan over medium heat. Cooking in batches and watching closely so they don’t burn, place half the zucchini in a single layer in the pan and cook until golden brown, about 4 minutes. Sprinkle with salt and pepper, then flip and cook 4 minutes. Transfer to a bowl or plate. Adding more olive oil to the pan if needed, repeat until all zucchini slices are cooked. When done, top with parmesan and serve.