Cook chocolate, 2 cups sugar and milk in a double boiler until chocolate is melted and sugar is dissolved. Then add cinnamon and 1 cup of sugar (1 1/2 cups if you use brown sugar). Boil, stirring only to avoid sticking, until mixture begins to thicken. Remove from heat. Cool to tepid, having added butter. Stir in nuts and candied fruit. Spoon into buttered tin or platter. Sprinkle with red or green sugar, if desired. Cut into squares when hardened.