In a medium-sized bowl, add the drained chicken, mayonnaise, Greek yogurt (or sour cream), Dijon mustard, kosher salt, black pepper, and onion powder.
Use the back of a fork to break up the chicken and mix until everything is well combined and creamy.
Add chopped apple, dried cranberries, and chopped pecans to the bowl.
Fold all ingredients together with a spatula until well mixed and evenly coated.
To assemble sandwiches, slice croissants or your chosen bread in half horizontally.
Place greens (spinach, lettuce, or spring mix) on the bottom half of the bread.
Scoop about 1/2 cup of chicken salad mixture onto each sandwich.
Replace the top half of the bread, cut the sandwich in half, and secure with toothpicks if needed.
Serve immediately and enjoy.