01 - Preheat your oven to 375°F. Grease a 9x13-inch baking dish with butter or cooking spray.
02 - Cook the pasta in salted boiling water according to package instructions until al dente. Drain well and set aside.
03 - In a large skillet over medium heat, sauté the diced onion in a splash of oil or butter for 3 minutes until soft. Add minced garlic and cook for 1 minute until fragrant.
04 - Stir in the cooked chicken, crumbled bacon, thawed peas, salt, black pepper, smoked paprika, and dried thyme. Remove from heat.
05 - In a large bowl, whisk together sour cream, softened cream cheese, whole milk, and 2 cups shredded cheddar cheese until smooth and well combined.
06 - Add the drained pasta and chicken mixture to the bowl with the cheese sauce. Stir until everything is evenly coated and combined.
07 - Transfer the mixture to the prepared baking dish and spread evenly into a uniform layer.
08 - In a small bowl, combine panko breadcrumbs, melted butter, and 1/2 cup shredded cheddar cheese. Mix until the breadcrumbs are evenly coated.
09 - Sprinkle the breadcrumb mixture evenly over the casserole. Bake for 25-30 minutes until the topping is golden brown and the casserole is bubbling around the edges.
10 - Let the casserole cool for 5 minutes before serving to allow it to set slightly for easier scooping.