In a big bowl, gently stir together your chosen binder, salt, pepper, allspice, and optional nutmeg.
Whisk in the 1/4 cup heavy cream, egg, and the grated onion (if you're using it for extra juiciness!).
Carefully mix in the ground beef just until everything is combined. Be careful not to overmix, as this keeps your meatballs wonderfully tender!
Roll the mixture into neat 1-inch balls and place them on a baking sheet.
Heat the olive oil in a large pan over medium-high heat. Cook the meatballs in small batches for about 3-4 minutes per side until they're beautifully browned and cooked through. Transfer them to a plate and cover to keep them warm.
Wipe out the pan, then melt the butter over medium heat.
Pour in the beef bone broth and 1/2 cup heavy cream. Bring it to a boil, then reduce the heat and let it gently simmer for 10-12 minutes, allowing the liquid to reduce by half for a concentrated flavor.
Lower the heat to low (no more simmering!). Stir in the cream cheese chunks until the sauce is wonderfully smooth and silky. If it's too thick, add a little extra cream or broth until it's just right.
Return the browned meatballs to the pan, coating them generously in the creamy sauce. Serve immediately and enjoy!