Season the ground beef with pepper, vegetable stock powder, paprika powder, and garlic. Refrigerate for at least 10 minutes.
Wash the mushrooms and cut into small pieces. Chop the onions into small pieces.
Melt 50 g butter in a large pan over medium-high heat. Add the onions and cook for 5 minutes, stirring occasionally. Add the mushrooms and cook for another 5 minutes. Add the ground beef and cook, breaking it apart, for 8–10 minutes until no longer pink. Pour in 1 liter gravy and stir to deglaze the pan. Reduce heat to medium and simmer for 15–20 minutes until the sauce thickens.
Serve with mashed potatoes and a fresh salad of your choice.