Line an 8x8 inch baking pan with aluminum foil, allowing foil to hang over the edges. Grease the foil.
In a medium bowl combine confectioners' sugar, cocoa and cinnamon.
Heat butter and milk in a medium saucepan over medium heat. When butter is melted stir in vanilla. Remove from heat and stir in sugar mixture and walnuts.
Pour into prepared pan. Refrigerate for 1 hour, or until firm.
Lift foil out of pan. Cut fudge into 2 inch squares, and then cut in half diagonally to make triangles.