Whisk eggs and milk in large bowl until blended. Stir in onion mixture, cheese, peas and parsley. Heat remaining dressing on medium-high heat in same skillet. Add egg mixture; cook 4 min. or until partially set, occasionally lifting edge with spatula and tilting skillet to allow uncooked portion to flow underneath. Cover; cook on low heat 10 min. or until centre is set. Meanwhile, heat broiler.