In Heavy Saucepan over medium heat, combine the butter, brown sugar, salt, sweetened condensed milk and corn syrup.
Bring to a boil, stirring constantly
Heat to between 235 and 240 degrees F
Remove from the heat and stir in vanilla (stir until bubbles are out)
Line a half size jelly roll pan with parchment paper (do not use wax paper) and pour the caramel into the pan. (You can use a full size jelly roll pan if you double this recipe)
Cool completely then cut (you can put in fridge to cool)
Cut candy into 1" squares and wrap tightly in 3" wax paper squares or pre-cut candy wrappers