01 - Preheat oven to 375°F. Grease a 9x13-inch baking dish with butter or cooking spray.
02 - Bring a large pot of salted water to boil. Cook pasta according to package directions until al dente. Drain well and set aside.
03 - In a large skillet over medium heat, cook onion in oil or butter for 3 minutes until softened. Add garlic and cook 1 minute until fragrant.
04 - Add cooked chicken, bacon, peas, salt, pepper, smoked paprika, and thyme to the skillet. Stir well and remove from heat.
05 - In a large bowl, whisk together sour cream, softened cream cheese, milk, and 2 cups cheddar cheese until smooth and creamy.
06 - Add drained pasta and chicken mixture to the cheese sauce. Stir until evenly combined and coated.
07 - Pour the mixture into the prepared baking dish. Spread evenly with a spatula.
08 - In a small bowl, combine panko breadcrumbs, melted butter, and remaining 1/2 cup cheddar cheese. Mix until crumbly.
09 - Sprinkle the breadcrumb mixture evenly over the casserole. Bake for 25-30 minutes until bubbling and golden brown on top.
10 - Remove from oven and let rest for 5 minutes to set before serving.