In a large bowl, cream butter and brown sugar until light and fluffy. Beat in the sour cream, egg and vanilla. Combine the flour, baking powder, baking soda and salt; gradually add to creamed mixture and mix well. Stir in cranberries and cashews.
Drop by tablespoonfuls 2 in. apart onto ungreased baking sheets. Bake 375° for 10-12 minutes or until lightly browned. Remove to wire racks to cool. Combine the glaze ingredients; drizzle over cookies.