Bring a pan of salted water to the boil and blanch the peas in it until half cooked, 2–3 minutes. Refresh briefly in cold water. Drain and reserve.
Melt the butter in a heavy pan and sweat the shallots in it until soft. Add the bacon and continue cooking for 3 minutes. Add the lettuce, peas and cream. Bring to the boil, reduce the heat and simmer gently until the peas are cooked, about