In a large mixing bowl, beat together the mayonnaise, softened cream cheese, lemon juice, garlic powder, ranch seasoning, salt, and pepper using a hand mixer (or stand mixer) until smooth and creamy. Taste and adjust the ranch seasoning if needed.
Fold in the chopped chicken, crumbled bacon, diced jalapeños, shredded cheddar cheese, and chopped cilantro until everything is evenly combined.
Cover and refrigerate for at least 1 hour to let the flavors come together. If you have time, chilling it overnight makes it even better.
Just before serving, make the panko topping. Melt the butter in a skillet over medium-low heat, then add the panko. Cook, stirring often, until golden brown and crispy, about 5 minutes. Remove from heat and let cool slightly.
Spoon the chicken salad into a serving bowl and sprinkle the toasted panko over the top. You can also stir a little of it directly into the salad for extra crunch. Garnish with more cilantro, jalapeños, or bacon if you like, and serve.