Preheat oven at 375F. Grease a cookie sheet and set a side.
In a big bowl beat butter and sugar until creamy. Add the egg and vanilla mix well. Add the flour, baking soda and salt. Put the cookie dough in the fridge for 1 hour.
Break in chunks the chocolate bar and put the cinnamon sugar in a shallow plate. Make a ball with the dough ,then flat the ball, put a chocolate chunk in the center, cover the chocolate with the dough and form into a ball again. Roll the balls into the cinnamon sugar.
Place the balls in the cookie sheet at least 2 inches apart. Bake for 15 minutes or until golden.