½ cup canola mayonnaise
½ cup plain whole-milk Greek yogurt
1 tablespoon fresh lemon juice (from 1 lemon)
2 teaspoons Dijon mustard
½ teaspoon black pepper
5 cups chopped rotisserie chicken breast
½ cup diced celery
1 cup halved red seedless grapes
¼ cup sliced scallions, divided
1 head butter lettuce
Stir together mayonnaise, yogurt, lemon juice, Dijon and pepper in a large bowl until combined. Add chicken, celery, grapes and 3 tablespoons scallions, and toss to combine. Serve on butter lettuce leaves, and top with the remaining scallions.