Preheat the oven to 375°F (190°C). Sprinkle the chicken breasts with salt and pepper, then place them on a baking sheet.
Bake for 25–30 minutes, or until the internal temperature reaches 165°F (74°C). Remove from the oven and let the chicken cool.
While the chicken is baking, whisk together mayonnaise, Greek yogurt, lemon juice, honey, garlic powder, salt, and pepper in a medium bowl until smooth and well combined.
Once cooled, shred the chicken using a fork or chop it into small pieces.
In a medium bowl, combine the shredded chicken, prepared dressing, celery, dried cranberries, and pecans. Stir the mixture until all the ingredients are evenly coated.
Place a lettuce leaf on each croissant or slice of bread. Evenly divide the chicken salad mixture among the croissants or bread slices, spreading it out for an even layer.
Serve immediately, or refrigerate until ready to eat. Enjoy your creamy, crunchy, and delicious Chicken Salad Croissant Sandwich!