In a heavy saucepan, bring the butter, brown sugar, and buttermilk to a boil. Lower the heat and continue a gentle, rolling boil for 2 1/2-3 min. Remove from heat and add the rum flavoring and chocolate chips. Stir with a wooden spoon until all the chips are melted and the mixture is smooth. If the mixture thickens too quickly, add 1 tbsp buttermilk. Fold in the coconut and pecans. Working quickly, drop by teaspoonfuls onto a large cookie sheet, covered with lightly sprayed waxed paper. Allow to sit 10-15 minutes or until completely set. Move chocolate drops to a wire rack to finish drying on the bottom.