Melt 2 tablespoons butter in a large skillet over med-high heat. Add onion, a sprinkle of salt, and cook 3-4 minutes until soft. Add the mushrooms, another sprinkle of salt, and stir and cook until beginning to release their liquid and starting to brown, about 4 minutes.
Add remaining tablespoon of butter, then add the chicken, flour and paprika. Season with 1 teaspoon salt and 1/4 teaspoon pepper. Cook, stirring, until the chicken browns, about 5 minutes or so.
Add the chicken broth and Worcestershire sauce and bring to a simmer. Stir, scraping up all the brown bits. Lots of flavor here and I often use a metal spatula to get up all the bits. Cook until thickened, about 5 more minutes.
Stir in the sour cream and season with salt and pepper. Continue simmering until chicken is cooked through, about 2-3 more minutes.
In serving bowl, top cooked egg noodles with the chicken mixture and chopped parsley. Sprinkle with additional paprika if desired.