One of my favourites is the AGA one.
Draw out fat from 1lb Beef Mince on gentle heat - add chopped Onion & fry quickly - add 1/4pt Beef Stock, cover & simmer 20min - remove from heat & add 2tbs Fresh Breadcrumbs, s&p.
Make 3/4pt White Sauce. Add 1tsp Dijon Mustard & pinch Nutmeg.
Peel Marrow, cut into 1" rings, deseed & blanch 4-5min till still just crisp - drain & arrange in pan - pile in Mince/Onion mix - spoon over sauce - scatter over 4oz grated Cheddar.
Cook 30min till golden.