Lots of butter, fresh cream and egg yolk - just the way things used to be done in the old days in the Loire Valley in France. This recipe must be tried, if only once in a lifetime.
Put half the butter and the bay leaves in a heavy pan.
Tear lettuce leaves and put them in the pan. Spread diced ham, peas and remaining butter evenly. Salt and pepper to taste (remember the ham is already salty).
Cover and cook on low heat. (Heating slowly allows the lettuce to yield enough water in which the peas will simmer. Check regularly and shake the pan gently if necessary - resist the temptation to stir.)
Meanwhile, beat all remaining ingredients together in a bowl. When peas are cooked (15-20 minutes), pour cream mixture all over. Shake gently so that cooking juices mix well with the thick cream. Remove from heat as soon as it begins to boil. Serve.