Heat a large frypan over medium-high heat; stir in the beef mince, chicken stock, garlic powder, black pepper and onion powder. Cook and stir until the beef is crumbly, evenly browned and no longer pink, about 7 minutes.
Stir in the flour and cook for 3 minutes, stirring constantly. Stir in the milk and bring to a simmer, stirring constantly. Reduce heat to medium-low and simmer 5 minutes to thicken. Serve on slices of toast.