Preheat your oven to 375°F.
Lightly grease a 9x13-inch baking dish with nonstick spray and set it aside.
In a large bowl, combine ground beef, breadcrumbs, beaten egg, grated onion, nutmeg, garlic powder, salt, and pepper. Mix until well combined.
Scoop about 1 ½ tablespoons of the mixture and roll into meatballs.
Heat olive oil in a large skillet over medium-high heat.
Add the meatballs and brown on all sides. (They will finish cooking in the oven.)
Remove the meatballs from the skillet and set them aside on a plate.
Meanwhile, boil a large pot of salted water and cook the egg noodles 2 minutes less than the package instructions. Drain and set aside.
Using the same skillet you browned the meatballs in, pour in the beef broth, heavy cream, and Worcestershire sauce.
Scrape up any browned bits from the bottom of the skillet.
Let the sauce simmer until slightly thickened, about 10 minutes.
Season to taste with salt and pepper.
Spread the cooked noodles evenly in the prepared baking dish.
Nestle the meatballs among the noodles.
Pour the sauce evenly over the dish.
Sprinkle grated Swiss cheese over the top.
Bake in the preheated oven until the cheese is melted and bubbly, about 20 minutes.
Let the casserole rest for 5 minutes before serving.
Garnish with chopped fresh parsley and enjoy!
