Prepare ratatouille: Place 1 tablespoon olive oil in large pot and heat over medium-high. Add onion and garlic; sauté until translucent, about 3 to 5 minutes. Add zucchini, squash, eggplant, peppers and tomatoes; cook until softened, about 10 minutes, stirring often. Season with salt, pepper, rosemary and thyme. Cook a minute or two longer. Remove from heat and set aside.
Cook pasta according to package directions. Drain and set aside.
Prepare cheese sauce: Melt butter in a medium saucepan over medium heat. Whisk in flour; cook 1 minute. Slowly add milk, while whisking, until well combined. Cook on low, stirring, until thickened, about 10 minutes. Stir in 1 teaspoon salt, 1/2 teaspoon black pepper, mustard powder, cayenne and oregano; remove from heat. Add cheeses; stir with wooden spoon until melted.
Combine pasta, cooked vegetables and cheese sauce in large pot. Stir until well combined. Cook over low heat about 5 minutes. Add basil and 1/4 cup fresh parsley and stir well to combine.
For topping: Combine remaining 2 tablespoons olive oil, bread crumbs and 2 tablespoons parsley in small skillet. Cook until toasted, stirring often, about 2 minutes. Sprinkle topping over hot mac and cheese. Serve immediately.