Butter the aluminum foil in the bread pan well with at least ½ tablespoon of butter. Keep it nearby as the caramel cooks.
Over medium heat, combine the sugar, cream and corn syrup. Cook until the sugar has dissolved and started to brown. Once the color of the sugar is a light tan color (I like to think of it as a “blonde wood” color) start adding the butter pieces, one by one, stirring fully after each piece melts before adding another one. Once all the butter is added, do the same process with the chocolate. Continue stirring until the chocolate is fully melted into the caramel, then turn the heat down to low.
Let the mixture cook on a low boil, stirring often. When the caramel reaches soft ball stage (see note), or about 240*F with a candy thermometer, it’s ready to be poured.
Carefully pour the hot caramel into the bread pan, gently smoothing the corners in to be filled. Sprinkle the kosher salt on top, as much as desired- I use about a tablespoon. Let the caramel sit overnight in a place where it will not be disturbed.
In the morning, remove the caramel by lifting it out of the bread pan by the foil and inverting it onto a cutting board. Peel away the foil, slice and wrap caramels. They will last up to a week if wrapped and kept tightly covered