For the meatballs: – 2 large eggs well beaten – 1/2 cup panko breadcrumb – 2 tablespoons ketchup – 1 tablespoon light brown sugar packed – 1 tablespoon Worcestershire sauce – 1 tablespoon garlic powder – 1 tablespoon onion powder – 1/2 teaspoon kosher salt – 1/2 teaspoon black pepper – 1/2 teaspoon smoked paprika – 2 pounds lean ground beef – oil for frying For the gravy – 6 tablespoons unsalted butter – 1 medium sweet onion thinly sliced – 1/2 teaspoon kosher salt – 1/2 teaspoon black pepper – 4 cloves garlic minced – 6 tablespoons all-purpose flour – 4 cups beef stock – 2 teaspoons Worcestershire sauce – fresh chopped parsley for garnish, optional