Make the meatballs:
Spray a 7 quart slow cooker with non stick spray to coat.
Add all meatball ingredients to a large mixing bowl, and mix together with hands until homogenous and well combined. Do not over mix.
Form mixture into balls (about 1 tablespoon each), and roll between your hands until smooth and well formed. Place in bottom of crockpot layering as needed.
Make the sauce and cook meatballs:
Whisk Worcestershire sauce, Kitchen Bouquet, beef stock, half and half, melted butter, nutmeg, and dijon mustard until well combined. Pour the mixture over the meatballs, cover, and cook for 3-4 hours on high, until meatballs are cooked through.
Finish and serve:
Once meatballs are cooked through, In a small bowl or liquid measure, whisk together 4 tablespoon cornstarch and 4 tablespoon water to make a slurry to thicken the sauce.
Add ⅔ cup sour cream and a ladle of warm sauce to the slurry and whisk well to combine. Adding the ladle of warm sauce keeps the sour cream from breaking in your finished sauce.
Pour the slurry/sour cream mixture into slow cooker, and stir well to combine.
Cover, and cook 5-10 minutes more, until sauce is thickened to desired consistency.
Serve meatballs hot over noodles or with mashed potatoes.
Makes about 50 meatballs.