Tear the bread into pieces and place in a small mixing bowl along with the milk. Set aside and soak

In a  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 mixer, Add the bread and milk mixture, ground chuck, pork, egg yolks,
1 teaspoon salt, black pepper, allspice, nutmeg, and onions. Beat on medium speed for 1 to 2 minutes.

 Make meatballs into small round balls and place on a sheet pan. Using the palm of your hands, shape the meatballs into rounds balls.

Heat the remaining butter in the  pan over medium-low heat,  Add the meatballs and saute until golden brown on all sides,  .  Once all of the meatballs are cooked, lower 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.  cover the meatballs with the gravy.