Bring a large pot of salted water to a boil. Add the egg noodles and cook according to the package instructions until tender but still slightly firm. Reserve a little cooking water, then drain the noodles and set them aside.
In a bowl, combine the onion powder, paprika, salt, and black pepper. Add the chicken pieces and toss until evenly coated with the seasoning.
Heat the olive oil in a large skillet over medium-high heat. Add the seasoned chicken in a single layer and cook for 6–8 minutes, turning occasionally, until golden brown and cooked through. The chicken should reach an internal temperature of 165°F (74°C). Transfer it to a plate and keep warm.
Reduce the heat to medium and melt the tablespoon of butter in the same skillet. Add the sliced mushrooms and cook for 4–6 minutes, stirring occasionally, until tender and lightly browned. Stir in the minced garlic, dried thyme, and oregano, cooking for another 30 seconds until fragrant.
Pour in the chicken broth and scrape up the flavorful browned bits from the bottom of the skillet. Let the broth simmer for about 3–4 minutes, then stir in the heavy cream. Simmer gently for another 3–5 minutes, until the sauce begins to thicken. Season with salt and black pepper to taste.
Return the cooked chicken and any accumulated juices to the skillet. Stir gently to coat the chicken in the creamy mushroom sauce and let everything simmer for 1–2 minutes until warmed through.
In the drained noodle pot, melt the remaining 2 tablespoons of butter over low heat. Stir in the chicken bouillon powder, if using, and add a splash of reserved noodle water. Add the cooked egg noodles and toss until evenly coated in the buttery mixture.
Sprinkle the Parmesan cheese over the noodles and toss again until the cheese melts and coats the noodles. Add a little more reserved cooking water if needed to keep them moist and glossy.
Divide the buttered noodles among serving plates and spoon the chicken and creamy mushroom sauce over the top. Finish with chopped fresh parsley and extra Parmesan, if desired. Serve warm.