Heat butter and olive oil in a large skillet over medium heat. Add chicken and season with garlic powder, onion powder, Italian seasoning, salt, and pepper. Cook until lightly browned.
Add diced onion if using and cook 2–3 minutes until softened.
Stir in minced garlic and cook 1 minute until fragrant.
Pour in chicken broth and milk, stirring well.
Add the uncooked egg noodles and press them into the liquid so they're submerged.
Bring to a gentle simmer, cover, and cook 8–10 minutes, stirring occasionally, until noodles are tender.
Stir in the remaining 2 tablespoons of butter to finish the sauce and make the noodles silky.
Let simmer 1–2 minutes to thicken slightly.
Garnish with parsley or Parmesan and serve warm.
