01 - Bring a large pot of salted water to a rolling boil. Add the egg noodles and cook according to package directions until al dente. Drain through a colander and set aside.
02 - While the noodles cook, melt the butter in a large skillet over medium heat. Add the chopped onion and sauté until soft and translucent, about 3 to 4 minutes. Add the minced garlic and cook for an additional 30 seconds until fragrant.
03 - Sprinkle the flour evenly over the onion mixture. Stir constantly for 1 minute to form a smooth roux and cook off the raw flour taste.
04 - Gradually whisk in the whole milk and broth, stirring until the mixture is smooth and free of lumps. Bring to a gentle simmer and cook for 3 to 4 minutes until the sauce has slightly thickened.
05 - Stir in the heavy cream, salt, black pepper, and garlic powder. Cook for 2 more minutes, then add the grated Parmesan cheese. Stir continuously until the cheese has fully melted and the sauce is creamy and smooth.
06 - Add the drained egg noodles to the skillet. Toss gently to coat every noodle evenly with the creamy sauce.
07 - Taste the finished dish and adjust seasoning with additional salt or pepper as needed. Serve immediately, garnished with fresh chopped parsley and extra Parmesan cheese if desired.