In a large bowl, combine ground beef, ground pork, breadcrumbs, milk, egg, salt, pepper, and nutmeg. Mix gently until just combined. Do not overmix.
Roll the mixture into 1-inch meatballs. You should get about 20-24 meatballs.
Heat 1 tablespoon of oil in a large skillet over medium-high heat. Brown the meatballs in batches, turning to brown all sides. Remove meatballs from skillet and set aside.
Gravy Preparation
In the same skillet, melt the butter over medium heat. Whisk in the flour and cook for 1 minute, stirring constantly.
Gradually whisk in the beef broth until smooth. Bring to a simmer, stirring frequently.
Stir in the heavy cream, Dijon mustard, salt, and pepper. Continue to simmer for 5-7 minutes, or until the gravy has thickened.
Return the browned meatballs to the skillet with the gravy. Reduce heat to low, cover, and simmer for 10-15 minutes, or until meatballs are cooked through and heated.
Serving
Serve hot, usually with noodles or mashed potatoes.
Notes
Garnish with fresh parsley if desired. These meatballs also freeze well.