Using a large mixing bowl, combine the ground pork, ground beef, onion, bread crumbs, heavy cream, egg, garlic, Worcestershire sauce, salt, pepper, allspice, and nutmeg.

Line a baking sheet with parchment paper. Set it aside.

Using a 1½ tablespoon scoop, scoop out the meat mixture. Roll into a ball. Repeat until all the meat mixture is shaped.

Using a 12-inch skillet, over medium-high heat, add the extra virgin olive oil.

Brown the meatballs on both sides, then line the browned meatballs in the bottom of a 6 to 7 quart slow cooker. A few of the meatballs may have to sit on top of the others.

Keeping the skillet on medium-high heat, add the butter.

Whisk the butter and leftover olive oil. Be sure to scrape the tasty brown bits left in the pan.

Whisk the flour into the oil/butter. Continue to whisk and cook the flour for 1 minute.

Whisk in the beef broth, Worcestershire sauce, kosher salt, and cracked pepper. Cook for 2 to 3 minutes.

Remove the pan from the heat. Carefully pour the sauce over the meatballs. Cook on high for 3 hours.

Keep the slow cooker temperature on high. Using a slotted spoon or tongs, remove the meatballs from the cooker.

Whisk in the heavy cream and sour cream. Replace the lid to the cooker and cook the sauce for an additional 30 minutes.

Turn the cooker off and add the meatballs back into the sauce. Evenly sprinkle the chopped fresh parsley. Serve while hot.