Add olive oil to a heavy bottomed pan over medium heat. Then add onion and a pinch of salt. Cook down, stirring often, for 3 minutes.
Add butter, garlic, mushrooms, thyme, and another pinch of salt and cook down for another 3 minutes or until garlic is fragrant and mushrooms are starting to caramelize.
Add the meatballs and a little bit of the stock to deglaze the bottom of the pan - scraping up any bits that are stuck on the bottom of the pan.
Now add the noodles, the rest of the beef broth and the Worcestershire and bring to a boil.
Reduce heat to medium and simmer with the lid slightly ajar for about 10 minutes, stirring often, or until the noodles are cooked through.
Stir in the sour cream and cream cheese then serve.
Season with salt and pepper if needed.