Bring a pot of water to a full boil and season liberally with sea salt.

Once the water is boiling, carefully place the chicken inside the pot and reduce the heat to medium. Simmer for 5 minutes, then remove the pot from the heat, cover it with a lid, and allow the chicken to sit in the hot water for 15 to 20 minutes, or until it reaches an internal temperature of 160 degrees F.

To verify the chicken is cooked through, insert a meat thermometer into the thickest part of the breasts. 

Transfer the chicken breasts to an airtight container and refrigerate until they are completely chilled.

Once the chicken has cooled, chop the chicken into bite-sized chunks. Transfer the cooked chopped chicken to a large mixing bowl, along with the apple, grapes, celery, and pecans. 

Add the mayonnaise and Greek yogurt and stir well until everything is well coated in the creamy dressing.

Sprinkle sea salt and black pepper over the chicken salad, mix well, and taste before adding any more. Serve the Waldorf chicken salad over a bed of greens or make lettuce wraps using butter lettuce or greens of choice.