Cook pasta according to package directions; drain, reserving 1/4 cup cooking liquid; return pasta to pot. Meanwhile, in a large skillet heat oil until hot. Add mushrooms, green onions and garlic; cook, stirring frequently, until mushrooms are tender, 5 to 6 minutes.

Stir in tomato, basil and salt; cook until tomato is just warm, about 1 minute. To pasta in pot stir in ricotta cheese and enough cooking liquid to make a creamy sauce. Add mushroom mixture; toss.