Start by preheating your oven to 375°F (190°C). Season both sides of the chicken breasts generously with salt and pepper, then place them on a lined or greased baking sheet. Roast the chicken for 25 to 30 minutes, or until the thickest part of each breast registers 165°F (74°C) using a meat thermometer. Remove from the oven and set aside to cool completely before handling.

While the chicken is in the oven, prepare the creamy dressing. In a medium mixing bowl, whisk together the mayonnaise, Greek yogurt, lemon juice, honey, garlic powder, and a pinch each of salt and black pepper. Whisk until smooth and well emulsified.

Once the chicken has cooled, shred it into bite-sized pieces using two forks or your hands. Add the shredded chicken to a large bowl. Mix in the chopped celery, dried cranberries, and pecans. Pour the prepared dressing over the top, and gently fold everything together until evenly coated and combined.

To assemble the sandwiches, lay a crisp lettuce leaf onto each halved croissant or slice of bread. Spoon a generous portion of the chicken salad mixture onto the lettuce, spreading it evenly from edge to edge. Close the sandwich with the top half and press lightly.

Serve immediately for a fresh, crunchy bite, or refrigerate for a chilled option later.