Cook and drain fettuccine as directed on package; cover to keep warm.
Meanwhile, in 2-quart saucepan, heat milk, cornstarch, basil, salt and pepper to boiling over medium-high heat, stirring constantly with wire whisk. Reduce heat to medium; simmer 2 to 5 minutes, stirring constantly, until sauce thickens. Remove from heat.
In blender or food processor, place 1/2 cup of the sauce, the ricotta cheese and 1/4 cup of the Parmesan cheese. Cover; blend on medium-low speed until smooth. Return mixture to remaining sauce in saucepan; stir well.
In nonstick 8-quart Dutch oven or stockpot, heat broth to boiling over medium-high heat. Add garlic; cook 2 minutes, stirring occasionally. Add mushrooms, broccoli and onions; cover and cook 4 minutes. Add pea pods and tomatoes; cook 1 minute longer. Add sauce and cooked fettuccine; heat until hot. Transfer to serving platter; sprinkle with remaining Parmesan cheese.