2cupsheavy whipping cream, divided (meaning, you'll add half at the beginning and half later)
2teaspoonspure vanilla extract
Line an 8X8-inch pan with parchment paper and set aside.
In a medium heavy-bottomed saucepan, combine the butter, salt, corn syrup, sugar and 1 cup of the cream. Over low heat, warm the ingredients until the butter is melted. Gently stirring during this part is ok to help combine the ingredients - just take care not to stir too vigorously and splash the liquid high up on the sides of the pan; also, take care to use low heat for this step. Too high of heat can cause the ingredients to melt unevenly and cause the butter to separate.
Once the ingredients are warmed and melted, increase the heat to medium-low (I keep my stovetop dial between a 3 and 4 the entire time; each stove is different so just keep an eye on the heat). Because these are no-stir caramels, too high of heat will burn the ingredients on the bottom. Moderate the heat of your stove so that the mixture maintains a simmer without burning. If you turn down the heat and the caramel stops simmering, simply increase the heat little by little until a good simmer is reached and then leave it there. You'll be good to go.
Clip a candy thermometer to the side of the pan and bring the mixture to a simmer. Cook, without stirring, until the mixture reaches 236 degrees F. Pour in the remaining 1 cup cream. Gently swirl the caramel once or twice with a wooden spoon or spatula to incorporate.
Again, bring the mixture to a simmer (don't adjust the heat to sharply - I keep mine set the same as before) and cook until the thermometer registers 245 degrees F.
Off the heat, carefully stir in the vanilla. It will bubble; just like before, just gently swirl with a spoon or spatula.
Immediately pour the caramel into the prepared pan - don't scrape the sides, just tip the pan until no more drizzles out. Let the pan of caramels cool completely at room temperature before cutting into pieces.