1Cook and drain fettuccine as directed on package.
2Meanwhile, in 12-inch skillet, heat oil and butter over medium heat. Cook onions and 1 tablespoon parsley in oil mixture about 4 minutes, stirring occasionally, until onions are tender.
3Stir in ricotta and feta cheeses; reduce heat to low. Cook about 2 minutes, stirring frequently, until cheeses are melted.
4Add fettuccine, Asiago and Parmesan cheeses and pepper to mixture in skillet. Cook about 4 minutes, tossing gently, until cheeses are melted and fettuccine is evenly coated. Sprinkle with parsley.