COOK and stir first 3 ingredients in skillet sprayed with cooking spray on medium-high heat 10 min. or until onions are crisp-tender.
COMBINE meat, potatoes and cheese in large bowl. Add onion mixture; mix well. Cool completely. Shape into 15 (3-inch) sausage-shaped croquettes. Dip, 1 at a time, in egg then in cracker crumbs, turning to evenly coat both sides of each croquette.
HEAT oil in large saucepan to 375°F. Add croquettes, in batches; cook 3 min. on each side or until golden brown on both sides. Drain on paper towels. Serve warm.