In a large mixing bowl, combine the ground beef, breadcrumbs, milk, egg, Worcestershire sauce, garlic powder, onion powder, salt, and black pepper. Mix gently with your hands until just combined, being careful not to overwork the mixture.
Shape the mixture into 12 equal-sized meatballs, about 1 1/2 inches in diameter, and set them aside on a plate.
Heat the olive oil in a large skillet over medium heat. Add the meatballs in a single layer and cook for 3-4 minutes per side, turning gently with tongs, until browned on all sides. Remove the meatballs from the skillet and set aside.
In the same skillet, whisk together the beef broth, flour, water, ketchup, and Dijon mustard until smooth. Bring the mixture to a simmer over medium heat, stirring constantly, until the sauce thickens slightly, about 2-3 minutes.
Return the meatballs to the skillet, nestling them into the sauce. Reduce the heat to low, cover, and simmer for 10-12 minutes, or until the meatballs are cooked through and the sauce is rich and glossy. Serve warm.