Whisk the egg and cream together in a medium bowl. Stir in bread until it is well coated and set aside.
Using a stand mixer with paddle attachment, beat the pork, onion, garlic, nutmeg, allspice, black pepper, brown sugar, salt and baking powder together on high speed until smooth for about 2 minutes.
Stir the bread mixture once more, breaking up any larger chucks of bread, then add it to the pork. Beat on high speed until smooth, about 1 minute, scraping the bowl as needed.
Add the beef to the pork mixture and beat on medium-low speed just until combined, about 30 seconds, scraping the bowl as needed.
Form 1-inch meatballs using a cookie scoop (with mechanical release) or by hand (moisten your hands first). Set the meatball on a baking sheet and continue to make 25-30 meatballs.
Heat oil in a 10-inch sauté pan over medium-high heat until it reaches a temperature of 350˚F and meatballs sizzle when placed in the pan. Add meatballs in a single layer without overcrowding them. Fry the meatballs in batches, flipping them half-way through cooking, for about 7-10 minutes or until cooked through. Adjust the heat as needed so the oil is sizzling, not smoking. Using a slotted spoon, transfer meatballs to a paper towel-lined plate. Repeat for the remaining meatballs.
Make the sauce: Pour off and discard the oil from the pan, keeping the brown bits that remain in the pan. Return the pan to medium-high heat and add the butter. Once the butter is melted, add the flour to make a light roux. Whisk constantly until the flour is well combined and lightly browned, about 1-2 minutes. Slowly whisk in broth, scraping the bottom of pan to loosen browned bits. Bring to a simmer and cook until sauce is reduced to about 1 cup. Stir in the Worcestershire, Dijon and cream, return to a simmer.
Add the meatballs to the sauce and simmer until heated through. Season with salt and pepper to taste. Garnish with parsley. Serve with mashed potatoes or egg noodles.