Begin by carefully removing the meat from your cooked chicken, ensuring to avoid any skin or bones. Shred the chicken as finely as possible.

In a medium bowl, whisk together the whole egg mayonnaise, sour cream, Dijon mustard, and lemon juice until smooth. Add onion powder, garlic powder, cooking salt, and black pepper, adjusting to taste.

In a large mixing bowl, combine the finely shredded chicken with your creamy sauce. Gently fold in the chopped celery, sliced green onions, crushed walnuts, diced pickles, and fresh dill until evenly coated.

Spread a thin layer of salted butter on one side of each slice of bread to prevent sogginess.

Evenly spread the creamy chicken filling on the buttered side of half of the slices. Top with another slice of buttered bread.

Refrigerate for at least 2 hours for neat edges and improved flavor.

Arrange the chilled sandwiches on a platter and serve.