In a large bowl, combine the beef mince, panko breadcrumbs, finely chopped onion, minced garlic, egg, ketchup, crumbled bouillon cube, Worcestershire sauce, and dijon mustard. Mix well until fully combined.

Shape the mixture into meatballs, about the size of a golf ball.

Heat the olive oil in a skillet over medium heat. Add the meatballs, cooking until browned on all sides. Once browned, remove the meatballs from the skillet and set them aside.

In the same skillet, melt the butter and sauté the sliced mushrooms until they’re golden brown. Add minced garlic and cook for another minute.

Sprinkle the flour over the mushrooms, stirring to combine. Gradually pour in the beef stock, whisking to avoid lumps. Stir in the additional dijon mustard and Worcestershire sauce, bringing the mixture to a simmer.

Return the meatballs to the skillet, ensuring they’re covered in the gravy. Cover and simmer for about 20 minutes, allowing the flavors to meld and the meatballs to cook through.

Plate the meatballs and drizzle with the rich gravy. Garnish with finely chopped parsley for color.