In a large heavy bottomed pan, melt butter over medium heat. Stir in sugar, milk, corn syrup and salt. Bring to a boil, stirring frequently. Continue cooking over medium-low heat, until a small amount of syrup dropped into cold water forms a *firm soft pliable ball, about 238°.
Remove from heat. Add food coloring and anise oil, and mix until the oil is completely incorporated. Pour into a buttered 9x13” glass pan. Let caramels cool over night.
Remove caramel from the pan, cut into 1 inch pieces. Wrap in 5x4 inch pieces of wax paper and twist the ends to enclose the caramel.
Notes
* a firm-ball 242°F (sea-level). That would make it about 232° at my altitude in Salt Lake about 4,000 feet, or 238° for a firm caramel.