Step 1: Prepare the Homemade Ranch Dressing
In a medium bowl, whisk together the mayonnaise, sour cream, milk, fresh chives, dill, parsley, garlic powder, onion powder, and lemon juice until smooth and well-combined. Season with salt and pepper to taste. For best flavor, let it sit for at least 10 minutes while you prepare the other ingredients.

Step 2: Chop the Main Ingredients
Finely chop the cooked chicken, celery, red onion, and pickles (if using). The goal is a uniform, small dice so that the mixture holds together well. Place them in a large mixing bowl.

Step 3: Combine the Filling
Add the crumbled bacon to the bowl with the chicken and vegetables. Pour the prepared ranch dressing over the top.

Step 4: Mix Gently but Thoroughly
Using a spatula, gently fold all the ingredients together until the chicken mixture is evenly coated with the ranch dressing. Be careful not to overmix and break down the chicken too much.

Step 5: Toast the Buns (Optional but Recommended)
Lightly toast your sandwich buns. This adds a nice textural contrast and prevents them from getting soggy from the filling.

Step 6: Assemble the Sandwiches
Place a lettuce leaf on the bottom half of each bun. Add a slice or two of tomato. Pile a generous amount of the chopped chicken bacon ranch mixture on top. If desired, add a slice of cheese.

Step 7: Serve and Enjoy!
Top with the other half of the bun, press down gently, and serve immediately