Mix butter, brown sugar, karo syrup and milk. Put in microwave for 1 to 1-1/2 minutes, stir for about a minute. Caramel mixture should be quite thin. Pour over graham crackers right away, and then sprinkle on chocolate chips.
Place under med. broiler for about 30-45 seconds, watch closely. Take out of oven and spread melted chocolate chips over the top. Great treats for the kids, mom and dad too!