Place the breadcrumbs in a large bowl. Using a standard box grater, grate the onion over the panko so it soaks in. Mix through.

Add remaining Meatball ingredients and mix well with your hands until thoroughly combined.

Roll 20 to 22 balls (1 ½ tablespoons of mixture).

Mix ingredients in a bowl until smooth. We will use this to thicken the gravy (no lumpy gravy, yay!)

Heat the oil in a large skillet over high heat. Cook meatballs, using tablespoons to roll until browned on the outside but still raw inside. Remove onto a plate and set aside.

Melt butter in the same skillet still on high. Cook mushrooms until they start to soften (~ 2 minutes). Add salt, pepper and the garlic, then cook for a further 2 minutes until the garlic is golden and mushrooms are soft.

Add beef stock, salt, pepper and slurry, then stir to combine.

Once the liquid starts to simmer, add meatballs and any juices pooled on the plate. Adjust heat to medium so it's simmering gently and cook for 5 minutes until gravy is thickened and meatballs are cooked through.

Serve over mash sprinkled with parsley if desired.