1. Heat the butter in a small skillet and add half the onion and garlic. Cook until wilted. Let cool briefly. 2. Put the meat in a mixing bowl and add the cooked onion and garlic, the bread crumbs, parsley, egg, half the cream and nutmeg. Mix well. Divide into 16 equal portions. 3. Flatten each portion into a small patty and place an olive in the center. Bring the edges of the meat together and seal in the olive. Press into a ball. 4. Heat the oil in a skillet large enough to hold the meatballs in one layer. Do not crowd them. Cook, turning often so that they brown evenly, about 5-10 min. Remove and keep warm. 5. Pour most of the fat from the skillet. To the skillet add the remaining onion and garlic and cook until wilted. Stir in the flour, then add the wine. Cook about 1 min., stirring. 6. Add the broth and tomato paste and stir with a wire whisk to remove any lumps. When the sauce is thickened and boiling, add the meatballs. Cover and cook 10 min., shaking the skillet occasionally. 7. Blend the remaining cream and the mustard into the sauce.