Preheat oven to 350°F. Grease a 9 x 13-inch baking dish or spray with nonstick cooking spray. In a large pot of well-salted boiling water, cook pasta according to package directions for al dente. Drain.
While the pasta cooks, heat olive oil in a large Dutch oven over medium heat. Add the turkey, onion, and mushrooms. Cook, breaking up the turkey with a wooden spoon, until the meat is no longer pink, and the vegetables are tender, about 7-10 minutes. Add the garlic and cook for 1 more minute. Drain off excess grease.
Stir in the Alfredo sauce, cooked rigatoni, broccoli, sundried tomatoes, shredded Parmesan, basil, parsley flakes, oregano, and a pinch of crushed red pepper flakes (these are spicy, so use sparingly). Stir until well combined. Taste and season with salt and pepper to taste; add extra red pepper flakes if you like it spicier.
Transfer the pasta mixture to the prepared baking dish. Sprinkle with the Italian cheese and finish with breadcrumbs on top. Cover with foil.
Bake the casserole for 25 minutes. Increase the oven temperature to broil. Uncover the dish and broil until the breadcrumbs are golden brown, about 1-2 minutes (keep a close eye on it the entire time since the breadcrumbs can burn quickly). Garnish with additional Parmesan and/or fresh herbs and serve!