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 thoroughly in 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 and garlic mixture. Stir constantly for 1 minute to cook out the raw flour taste and form a smooth roux.
04 - Gradually whisk in the whole milk and broth, pouring slowly while stirring to prevent lumps. Bring the mixture to a gentle simmer and cook for 3 to 4 minutes, stirring occasionally, until the sauce has slightly thickened.
05 - Stir in the heavy cream, salt, black pepper, and garlic powder. Continue cooking for 2 more minutes, then add the grated Parmesan cheese. Stir until the cheese is fully melted and the sauce is creamy and smooth.
06 - Add the drained egg noodles to the skillet, tossing gently to coat them evenly in the sauce. Taste and adjust seasoning with additional salt or pepper as needed.
07 - Serve immediately in warmed bowls, garnished with chopped fresh parsley and an extra sprinkle of Parmesan cheese if desired.