of large saucepan or skillet coated with cooking spray. Cook 3 minutes, stirring, then cover and reduce heat to low. Cook 5 to 10 minutes. Add greens; cover and simmer in their own juices until just tender. Drain. Melt butter in small saucepan. Gradually add flour; cook about 1 minute. Stirring constantly, add milk gradually; continue stirring until thickened. Stir in rosemary, Worcestershire and pepper. Pour sauce over greens and onions; gently blend.