In a large bowl, beat the butter, sugar and coffee until smooth. Beat in eggs and vanilla. Combine the flour, cocoa, cinnamon, baking powder and salt; gradually add to the sugar mixture. Stir in walnuts.
Spread into a greased 13x9-in. baking pan. Bake at 350° for 18-22 minutes or until a toothpick inserted in the center comes out clean (do not overbake). Cool on a wire rack. Dust with confectioners' sugar.