Add ingredients for meatballs except butter and olive oil to a large bowl, seasoning with salt and pepper. Mix with your hands or a large spoon until well combined and shape into golf ball sized meatballs.
Heat butter and olive oil in a large frying pan over medium heat. Fry meatballs until coloured and cooked through on one side, turn and fry on other side. Set aside.
Make gravy by heating butter in a pot until melted and foaming. Add mushrooms and onions. Sauté until softened and onions are starting to caramelise and add garlic. Sauté another minute.
Add beef bone broth and deglaze well to get any brown bits off the bottom of the pot and into the sauce. Bring to the boil.
Add and mix through Dijon mustard and cream. Season with salt and pepper. Bring to the boil again and then lower heat to a simmer to reduce, thicken and colour the sauce. Reduce by half or until thickened to your liking. Add and mix through meatballs.
Meanwhile make your fried cabbage while your sauce is reducing. Heat butter in a large pot until melted and foaming. Add shredded cabbage.
Mix cabbage over high heat to coat with the butter. When the cabbage has slightly cooked down and looks shiny, you can turn the heat down to medium and allow the cabbage to cook. Season with salt and pepper and stir occasionally until cabbage has browned and coloured.
Serve meatballs with mushroom onion gravy over fried cabbage.