4 1-ounce semisweet chocolate squares
1/2 cup packed brown sugar
3 tablespoons vegetable oil
1 egg
1/2 teaspoon vanilla
1/2 cup all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon salt
1/8 teaspoon cinnamon (optional)
1/2 cup chopped walnuts
1/2 cup confectioners’ sugar