01 - Preheat your oven to 200°C (400°F). Lightly grease a 23x33 cm (9x13 inch) baking dish.
02 - Boil the pasta in generously salted water until it is just al dente. Drain the pasta and set it aside.
03 - In a skillet, heat the olive oil over medium heat. Season the diced chicken with salt, black pepper, and garlic powder. Cook until the chicken is golden brown and thoroughly cooked through, approximately 5–7 minutes. Remove from skillet and set aside.
04 - In a saucepan, melt the butter over medium heat. Whisk in the flour and cook for 1 minute, stirring constantly.
05 - Gradually whisk in the milk. Continue to cook, whisking, until the sauce has thickened to a smooth consistency, about 3–5 minutes.
06 - Remove the saucepan from the heat. Stir in the shredded cheddar cheese, shredded mozzarella cheese, Dijon mustard, paprika, and dill. Season with salt and pepper to your preference.
07 - In a large mixing bowl, combine the cooked pasta, cooked chicken, prepared sauce, and chopped dill pickles. Mix thoroughly to ensure all components are evenly distributed.
08 - Transfer the combined pasta mixture into the prepared baking dish and spread it out evenly.
09 - In a separate bowl, combine the crushed pickle chips, panko breadcrumbs, and melted butter. Mix until well combined.
10 - Evenly sprinkle the Panko-pickle chip crust mixture over the surface of the pasta in the baking dish. Bake for 20–25 minutes, or until the topping is golden brown and the casserole is bubbling around the edges.
11 - Allow the casserole to rest for 5 minutes before serving. Garnish with additional fresh dill, if desired.