In a saucepan cook fresh asparagus, covered, in a small amount of boiling water 8 to 10 minutes or until done. Drain; set aside.
Meanwhile, cook tortellini or fettuccine according to package directions; drain.
For sauce, in a medium saucepan cook onion, mushrooms, and garlic in hot butter or margarine until tender but not brown. Stir in flour, salt, oregano, and pepper. Add milk. Cook and stir until thickened and bubbly, then cook and stir 1 minute more. Remove from heat.
Stir in cream cheese until melted. (Sauce will thicken.) Add asparagus, chicken, or turkey, parsley, and pimiento; heat through. Serve immediately over hot pasta. Makes 4 servings.