Preheat the oven to 325 degrees F (160 degrees C).
Line a baking sheet with aluminum foil for easy clean-up and place an ovenproof baking/cooling rack over top; spray rack generously with nonstick cooking spray.
Whisk the Egg (1) and Heavy Cream (1/4 cup) together in a medium bowl. Stir in the White Sandwich Bread (3/4 cup) and mash until no large bread chunks remain. Set aside.
In a stand mixer fitted with the paddle attachment, beat the Ground Pork (0.5 pound), Garlic (1 clove), Ground Allspice (1/8 teaspoon), Ground Black Pepper (1/8 teaspoon), Salt (3/4 teaspoon), and Baking Powder (1 teaspoon) on high speed until smooth and pale, about 2 minutes, scraping bowl as necessary.
Add the bread mixture to the mixing bowl and beat on high speed until smooth and homogeneous, about 1 minute, scraping the bowl as necessary.
Add the 85/15 Lean Ground Beef (0.5 pound) and mix on medium-low speed until just incorporated, about 20 seconds, scraping the bowl as necessary.
Using moistened hands (it's sticky and wet hands help; keep wetting them as you go), form the meat mixture into tablespoon-size round meatballs and place on the prepared rack. Bake for about 20 minutes, until just done.
Meanwhile, in a large sauté pan, mix together Ketchup (1/2 cup), Dark Brown Sugar (1/2 cup), Water (2 tablespoon), Apple Cider Vinegar (1 1/2 tablespoon), Worcestershire Sauce (2 teaspoon), Shallot (1 tablespoon), Garlic (1 clove), Ground Black Pepper (1/8 teaspoon), and Salt (1/2 teaspoon) for the sauce. Bring to a simmer and cook gently until thickened, about 10 minutes.
Add the baked meatballs to the sauce and stir to coat evenly.
Transfer the meatballs to a serving platter, spear with toothpicks and spoon the sauce over top. Garnish with Fresh Parsley (to taste), if desired. Serve warm and enjoy!