1. Melt butter in a medium saucepan over medium-high heat. Add onion to pan; sauté 5 minutes or until onion is tender. Sprinkle with flour; cook 1 minute, stirring onion mixture constantly. Add potato, milk, broth, and 1/2 cup water to pan; bring to a boil. Cover, reduce heat, and simmer 10 minutes. Add 1/2 cup reduced-fat sharp cheddar cheese and ground red pepper; cook 2 minutes or until cheese melts, stirring frequently. Top each serving evenly with 1 1/2 teaspoons chopped green onions.