Zucchini rounds are flattened, then coated with Parmesan cheese, lemon zest, garlic and basil for a savory summer side. The cheese browns nicely, giving them an almost-crispy topping.
Position oven rack 6 inches from broiler. Preheat to 400°F.
Score an X in the top of each zucchini round, cutting about halfway through. Arrange the rounds in a single layer on a large rimmed baking sheet. Drizzle with oil and sprinkle with salt and pepper. Bake on the upper rack until just tender, 10 to 12 minutes. Remove from oven and flatten the rounds with the bottom of a mason jar or sturdy glass. Turn broiler to High.
Meanwhile, combine lemon zest, garlic, Parmesan and basil in a small bowl. Sprinkle the mixture over the smashed zucchini. Broil until lightly browned and the cheese is melted, about 2 minutes.