Preheat oven to 350.
Boil the pasta in salted water, according to package directions.
Meanwhile, heat oil in a medium skillet over medium-high heat.
Season both sides of the chicken breasts with salt and pepper.
Cook, turning once for about 5 minutes on each side.
Transfer to a plate , cut into cubes and keep warm.
Drain pasta and return to the pot.
Stir in shredded cheese, butter, sour cream, and cream cheese, until creamy.
Add peas, carrots and chicken.
Transfer mixture to casserole dish and sprinkle breadcrumbs on top.
Bake uncovered for 30 minutes or until browned on top.
Serve hot.