1) Heat oven to 200C/180C fan/gas 6. 2) Put the oil in a saucepan with the onions and peppers and cook over a low heat for about 10 minutes. 3) Add the garlic, chorizo, herbs, spices and tomatoes and cook for 10 minutes more. Season to taste. 4) Scoop out the insides of the marrow and stuff with the tomato mixture. 5) Bake for 30 minutes covered with foil then sprinkle over the cheese and top with the breadcrumbs. 6) Bake for another 10 minutes until the cheese is melted and the breadcrumbs are golden.