Marlene's Chicken Waldorf Salad

INGREDIENTS

• 4 cups cubed, cooked chicken breast
• 1 (20 ounce) can pineapple chunks, drained
• 1 Red Delicious apple, chopped
• 1 Golden Delicious apple, chopped
• 1 cup sliced celery
• 1/2 cup seedless red grapes
• 1/2 cup seedless green grapes
• 1/2 cup chopped walnuts
• 3/4 cup milk
• 3/4 cup mayonnaise
• 1 (1 ounce) packet ranch dressing mix
• 6 leaves lettuce, or as needed