Cook the beans until they are almost tender. Drain them in a colander and dry them on kitchen paper towels. In a medium-sized saucepan, melt 1 ounce butter over moderate heat. Add the beans and 5 fluid ounces double cream or just enough to cover. Place the pan over moderate heat and simmer for 5 minutes, stirring frequently.
Pour the beans and sauce into a warmed serving dish and serve immediately.