Preheat oven to 200 degrees F.
Tear the bread into pieces and place in a small
mixing bowl along with the milk. Set aside.
In a 12-inch straight sided saute pan over medium
heat, melt 1 tablespoon of the butter. Add the onion and
a pinch of salt and sweat until the onions are soft.
Remove from the heat and set aside.
In the bowl of a stand mixer, combine the bread and
milk mixture, ground chuck, pork, egg yolks, 1 teaspoon
of kosher salt, black pepper, allspice, nutmeg, and
onions. Beat on medium speed for 1 to 2 minutes.
Using a scale, weigh meatballs into 1-ounce portions
and place on a sheet pan. Using your hands, shape the
meatballs into rounds.
Heat the remaining butter in the saute pan over
medium-low heat, or in an electric skillet set to 250
degrees F. Add the meatballs and saute until golden
brown on all sides, about 7 to 10 minutes. Remove the
meatballs to an ovenproof dish using a slotted spoon and
place in the warmed oven.
Once all of the meatballs are cooked, decrease the
heat to low and add the flour to the pan or skillet.
Whisk until lightly browned, approximately 1 to 2
minutes. Gradually add the beef stock and whisk until
sauce begins to thicken. Add the cream and continue to
cook until the gravy reaches the desired consistency.
Remove the meatballs from the oven, cover with the gravy