Brown ground beef with chili powder in 12-inch nonstick skillet over medium-high heat, stirring occasionally, about 5 minutes. Season, if desired, with salt and black pepper.
Drain tomatoes, reserving tomato juice. Add enough water to tomato juice to equal 1-1/2 cups. Stir tomato juice mixture, tomatoes, beans and corn into skillet. Bring to a boil.
Add Knorr® Pasta Sides™ - Cheesy Bacon Flavor Macaroni and return to a boil. Reduce heat to medium and cook uncovered, stirring occasionally, 10 minutes or until pasta is tender. Serve, if desired, with sour cream and chopped green onions.