Heat a large cast iron skillet (mine is 12" in diameter) or a large skillet with tall sides over medium heat. Add 1 tsp. of the olive oil to the warmed pan, and then add the meatballs. Using a tongs, turn meatballs every minute or two to brown all sides, cooking about 10 to 12 minutes total. The meatballs are already fully cooked, so it's just a matter of getting them nicely browned for extra flavor and texture. Remove browned meatballs to a plate.

Using the same skillet, over medium heat, add remaining tablespoon of the olive oil and one tablespoon of the butter. Once butter has melted, stir in onions, mushrooms, and garlic. Cook until onions are transparent and mushrooms are nicely softened, about 6 to 10 minutes.

Now slide everything in the skillet to one side. Add the remaining three tablespoons of the butter to other side of skillet. When butter is melted, sprinkle flour over the butter, whisking all the while - a flat whisk works awesome here! Draw as much butter as you can into the flour. Cook for 4 to 5 minutes, until the mixture is bubbling and slightly browned.

Stir in soy sauce and Worcestershire sauce to create a very thick mixture. Cook for 1 minute. Then slowly add milk while you whisk and scrape the bottom of the pan, smoothing out the mixture with the whisk. Once this mixture is smoothed out, whisk in broth to fully incorporate. Then bring the mushroom mixture into the milk mixture. Stir to incorporate. Cook until thickened, about 15 to 20 minutes. Then stir in sour cream and dried mustard. Taste test the gravy to see if more salt is needed - if so, add it now. Then season with finely ground black pepper and very coarsely ground black pepper. Add chicken meatballs to gravy, folding to incorporate. Cook for 5 to 10 minutes, to heat meatballs and gravy thoroughly, folding every few minutes.

Serve over cooked egg noodles. Garnish with fresh chopped parsley.