While pasta cooks, heat a large drizzle of olive oil in cast iron pan. Add zucchini, onion, garlic, and Italian Seasoning. Cook, until just browned, 4-6 minutes, season with salt and pepper. (This is where you would add this meat if you going that route)
Add sauce, cooked pasta, and reserved 1/2 cup of pasta cooking water to pan with veggies; lightly stir to combine.
Stir in half the Parmesan, season with plenty of salt and pepper. Remove pan from heat.
In a small bowl, stir together panko, remaining Parmesan, and a drizzle of olive oil. Top pasta with disks of mozzarella slices, then top with the panko mixture.
Place Cast Iron pan on top rack of oven on Broil until panko is golden brown, sauce is bubbly, and cheese has melted,approximately 5-7 minutes. You will want to watch carefully to avoid burning. Serve directly from pan and drizzle with remaining basil oil.