Melt the butter in a large pot over medium heat. Add the seasoned chicken breasts and cook until both sides are nicely browned and an instant-read thermometer registers 160°F (71°C).

Transfer the cooked chicken to a cutting board and let it rest for about 5 minutes to retain juices.

Using the same pot, add the mushrooms (if using), diced onion, celery, and carrots. Sauté until the vegetables soften, roughly 5–7 minutes. Stir in the minced garlic and cook until fragrant, about 30 seconds to a minute.

Pour in the chicken broth and the half-and-half, scraping the bottom of the pot to lift any browned bits. Increase heat to medium-high and bring the liquid to a gentle boil.

Cut the rested chicken into bite-size pieces and return them to the pot. Add the salt, black pepper, garlic powder, dried thyme, ground sage, cayenne, and paprika, stirring to combine.

Once the mixture is boiling, stir in the egg noodles. Reduce the heat to medium and simmer, stirring occasionally, until the pasta is mostly cooked—about 10–15 minutes depending on the pasta used.

Add the thawed corn, peas, and chopped parsley, then continue cooking until the noodles are tender and the sauce has thickened, about 6–8 more minutes. Keep in mind the sauce will firm up as it cools.

Remove the pot from the heat and serve immediately, topping portions with pie crust crumbles if desired for a pot-pie finish.