Wash and dry all produce. Bring a large pot of salted water to a boil. Preheat broiler to high. Cut zucchini into 1/4-inch cubes. Cut mozzarella into 1/2-inch cubes. Peel, halve, and chop onion. Mince or grate garlic. Pick half the basil leaves from stems and roughly chop (save the rest for garnish).

Once water boils, add penne to pot. Cook until al dente, 9-11 minutes. Carefully scoop out 1/2 cup pasta cooking water, then drain.

Meanwhile, heat a large drizzle of olive oil in a large pan over mediumhigh heat (use an ovenproof pan if you have one). Add zucchini and cook, tossing, until starting to brown, about 5 minutes. Toss in onion, garlic, and half the Tuscan heat spice (we’ll use the rest later). Cook, tossing, until onion is softened, 3-5 minutes. Season with salt and pepper.

Add marinara sauce, penne, remaining Tuscan heat spice, and reserved pasta cooking water to pan and stir to combine. Let simmer until warmed through, 3-4 minutes. Stir in chopped basil and half the Parmesan. Season with plenty of salt and pepper. TIP: If your pan is not ovenproof, transfer contents of pan to an 8-by-11-inch baking dish at this point.

Scatter mozzarella over pasta in pan or dish. Stir together remaining Parmesan, panko, and a drizzle of olive oil in a small bowl, then sprinkle over pasta.

Place pan or dish under broiler and broil until panko is golden brown and sauce is bubbly, 5-7 minutes. (TIP: Keep an eye out for any burning.) Let cool slightly. Tear remaining basil leaves from stems and scatter over top, then divide between plates and serve.