There are very few recipes that I am willing to break out the thermometer over. This is one of them. The caramel is so soft and gooey and sweet that it is well worth the effort.
1 cup butter
1 lb. brown sugar
dash of salt
1 cup light corn syrup
1 15 oz. can sweetened condensed milk
1 tsp vanilla
Melt butter in heavy saucepan. Add sugar and salt; stir thoroughly. Stir in corn syrup, mix well. Gradually add the milk, stirring constantly. Cook and stir over medium heat to firm ball stage (245 degrees). This will take 12-15 minutes. Remove from heat, stir in vanilla. Pour into buttered 9x9x2 inch pan. Cool and cut into squares. If you plan to give it away, it does well wrapped in individual pieces of wax paper.