Slice the marrow into rounds roughly 2 inches thick.
Scoop the seeds out of the middle so they make ‘O’ shapes.
Place on a lightly oiled baking tray.
Score the marrow deep so that it cooks all the way through and place in the middle of an oven at gas mark 5. This will take at least 30 mins.
When the marrow has been cooking for at least half the time, begin frying off the mince in a large pan. When the mince has browned, add the chopped onion and garlic, and let them soften.
Next add the yellow pepper and continue to fry for a further five mins before adding the mushrooms.
Once all the veg has begun to cook pour over the tinned tomatoes and stock, season and allow it to simmer for 10 mins.
When it has reduced down to a thick saucy consistency, take the marrow out of the oven and spoon the mince sauce into the hollowed out marrow.
Place this back into the oven for another 20 mins
Whilst the marrow finished cooking, melt the butter in a pan before adding the flour. Mix this into a smooth paste before adding the milk a splash at a time.
Each time you add more milk, ensure that the paste remains smooth. It will eventually become a thick sauce.
Once it has reached the consistency of a sauce, add the grated cheese and stir.
Allow the cheese to melt throughout the sauce before leaving to heat through slowly.
Make sure you stir the sauce often so no lumps form.
Once the marrow and mince mixture has cooked serve with a hearty drizzle of cheese sauce.