Place the bread, eggs, Parmigiano, and beef in a bowl and mix well.

Using your hands, shape into meatballs, about 2-1/2″ in diameter. If necessary, use a measuring cup to make each meatball 1/3 cup. Set the meatballs aside while you make the sauce.

Add the oil to a saucepan and warm over medium heat.

Add the onions, thyme, brown sugar, salt, and pepper. Stir well and cook for 3 minutes.

Increase heat to medium-high, add the Marsala wine, and stir until reaching a boil. Reduce heat to medium-low and cook until all the wine has evaporated and sauce is creamy.

Stir in the beef stock and bring to a boil over medium-high heat.

Add the meatballs and reduce heat to medium-low. Cook for 35-40 minutes. At this point the sauce should be reduced by 1/2 and intensely flavored.

Serve family style in a large bowl or on a tray topped with the Agglasatu sauce and, optionally, topped with chopped chives.