In a small bowl, beat butter and sugar until crumbly, about 2 minutes. Beat in egg. Combine the flour, salt and baking powder; add to butter mixture alternately with milk, beating well after each addition. Fold in cranberries.
Pour into a greased 9-in. square baking dish. Bake at 350° for 55-60 minutes or until a toothpick inserted near the center comes out clean.
In a small saucepan, melt butter; stir in brown sugar and cream. Bring to a boil, stirring constantly. Serve with warm cake. Yield: 12 servings.