Caramel

So I just took this from The American Homemaker. I've always wanted to make this and I don't want to lose this recipe. So here it is.

1 (14 oz) can sweetened condensed milk
2 c. sugar
1 c. butter
1/4 tsp salt
1 1/2 c. light corn syrup

Cook and stir constantly in heavy pan until the mixture reaches 240. (I love that she put this next part in, because I would have freaked out LOL) If you see flecks of brown, don't worry, just keep stirring- the whole thing will turn a darker caramel color. Take off stove and add 1 tsp vanilla. Pour into a buttered 9x13 pan and cool until the next day. Cut and wrap in wax paper.