Place an oven rack on the upper third of the oven. Turn the oven to broil.
Slice the zucchini into ¼-inch-thick rounds. Place the zucchini on a baking sheet. Brush both slides with the oil and sprinkle with the salt and pepper.
Broil until the zucchini is tender and lightly golden, 6 to 8 minutes, flipping once halfway through.
Top each zucchini round with some marinara sauce, mozzarella, parmesan, and a few mini pepperonis.
Broil until the cheese is golden and melted, 1 to 2 minutes. Sprinkle with parsley and serve.
