Here's one from Gary Rhodes I saw on tv last weekend (with my own added bits 'coz I can never follow a recipe without tweaking it!!!

) - tried it, super, simple and tasty!
Fry your sliced leeks and mushrooms in butter then place in a small dish.
Add a little double cream. Sprinkle on some grated cheese and then crack open an egg on top. Top up dish with a little more cream and season. Cook in a bain marie (snadger, thats a large dish with some hot water in it!) for around 15 minutes, oven temp 200C - serve hot with crusty bread to dip into your egg yolk! Yummy!

dexterdog