Potatoes and Mushrooms

10 small new potatoes
1/2 cup melted butter
2 Tbs green onion, chopped
1/2 lb mushrooms, sliced
1 cup meat stock
3 egg yolks
1 tsp lemon juice
salt and pepper

Cook potatoes in their jackets until tender. Drain and place in casserole dish. Add butter and chopped onion. In a bowl, beat egg yolk, add lemon juice, mushrooms, meat stock, salt and pepper and pour over potatoes. Bake uncovered at 350 for 30-40 minutes.