Wash and then cut the white part of the leeks into slices. Heat a frying pan and add a drizzle of olive oil. Fry the leeks gently for about 10 minutes until soft. Season with salt and pepper. Put to one side.
Grill the bacon rashers for 5 min. Put to one side.
Put the burger buns in the oven for 5 min.
Heat a frying pan and add a knob of butter. Once the frying pan is hot, sear the steaks. Season with salt and pepper.
Spread the lower buns with grain mustard. Add a few spinach leaves and place the steaks on top. Add the grilled bacon rashers and then the Roquefort and leeks. Close the burgers with the top bun.
Serve hot and accompany with homemade chips and a glass of India pale ale!