Cook pasta according to package directions until al dente.
Meanwhile, melt butter in small skillet; add carrot, bell pepper, zucchini, salt and pepper to taste. Cook over medium heat until vegetables soften but retain their bright color, about 5 minutes.
In small bowl, combine ricotta, cream and parmesan cheese; mix until smooth. Stir in lemon zest and juice.
Drain pasta and immediately toss with cheese mixture; stir in vegetables. Serve with additional parmesan cheese for topping.