In food processor, pulse basil, walnuts, Parmesan cheese, lemon juice, garlic, salt and pepper until combined. With motor running, slowly add oil in thin, steady stream until mixture is smooth. Transfer to bowl; set aside.
Preheat oven to 400°F (200°C). Grease baking dish; set aside. Cook pasta for 3 to 5 minutes or until tender but still firm, adding broccoli during the last 2 minutes of cooking time. Drain and reserve 1/3 cup (75 mL) of the cooking liquid.
Toss cooked pasta and broccoli with Pesto and reserved cooking liquid. Transfer half of the pasta mixture to prepared baking dish; dollop ricotta over top. Add remaining pasta mixture; sprinkle mozzarella and Parmesan over top.
Bake for 18 to 20 minutes or until cheese is melted and heated through. Just before serving, sprinkle with parsley.
Stir in cooked, sliced chicken breast along with pasta for added protein if desired.