Preheat oven: Set to 375°F (190°C). Lightly grease a 9×13-inch baking dish.
Cook pasta: Boil pasta in salted water until just al dente (1–2 minutes less than package directions). Drain and toss with olive oil to prevent sticking.
Mix filling: In a large bowl, combine pasta, chicken, Alfredo sauce, ricotta, half of the mozzarella, and spinach/broccoli (if using). Season with salt and pepper. Stir until well coated and creamy.
Assemble casserole: Spread mixture evenly into the baking dish. Sprinkle remaining mozzarella and Parmesan over the top. If using breadcrumbs, scatter them evenly for added crunch.
Bake: Cover loosely with foil and bake for 20 minutes. Remove foil and bake for another 10–15 minutes, until cheese is melted, bubbly, and golden brown.
Rest & serve: Let casserole sit for 5 minutes before serving to help it set. Garnish with parsley for a fresh finish.