CRANBERRY PUDDING: Cut cranberries in half. Sift flour and baking powder together. Stir in cranberries. Beat egg, salt, molasses, and hot water together and add the flour and cranberry mixture. Pour into an ungreased mold, cover with foil loosely, and steam for 1 1/2 hours until pudding is springy to touch and a toothpick comes out clean. BUTTER SAUCE: In a saucepan melt butter, and add sugar, cream and vanilla. Cream together over low heat until smooth and somewhat thick. Do not boil.