Heat oven to 350°. Cook broccoli spears according to package directions; drain well. Place ham slices on flat surface. Add a slice of cheese on top of each ham slice. Add broccoli spears to center. Roll and secure with a toothpick. Place rollups in a 9x13-inch baking dish. Cook onion in butter or margarine until tender. Blend in flour, salt and pepper. Add milk and stir until thickened. Pour over broccoli rollups. Bake for 30 minutes or until bubbly. Yields 12 servings.