Cook pasta according to package directions.
Drain, reserving 1 cup cooking liquid; keep warm.
In large Dutch oven over medium heat, cook onion and sausage 10 minutes or until sauce is browned.
Stir in kale; cover, simmer 5 minutes or until kale is tender.
Stir in pasta, reserved 1 cup reserved liquid and beans.
Sprinkle with cheese and pepper flakes.