In a microwave, melt butter and chocolate; stir until smooth. Beat in brown sugar and corn syrup until blended. Beat in egg. In another bowl, whisk flour, baking soda, 1 teaspoon cinnamon and salt; gradually beat into brown sugar mixture. Refrigerate, covered, until firm, about 1 hour., Preheat oven to 350°. In a shallow bowl, mix confectioners' sugar and remaining cinnamon. Shape dough into 1-1/2-in. balls; roll in confectioners' sugar mixture. Place 2 in. apart on greased baking sheets. , Bake until cookies are set and tops are cracked, 10-12 minutes. Cool on pans 2 minutes. Remove to wire racks to finish cooling.,