Preheat oven to 350 degrees (175 C.).

Cook noodles according to package directions; drain.

In a large skillet, melt butter over medium heat.

Add chopped onion and cook until tender.

Stir in condensed cream of mushroom soup, pimientos, and chopped pickled hot green chili peppers.

Grease a 4-quart casserole dish.

Layer half of the cooked noodles into the casserole dish.

Top with half of the cooked and cut-up chicken or turkey. Season with salt and pepper.

Add half of the soup mixture over the chicken layer.

Sprinkle half of the shredded sharp cheddar cheese over the soup mixture.

Repeat the layering process with the remaining noodles, chicken, soup mixture, and cheese.

Bake uncovered in the preheated oven for 45 minutes, or until golden brown and bubbly.