1 1/2 cups (360 ml) heavy 'whipping' cream (cream with a 35-40% butterfat content)
1 cup (200 grams) granulated white sugar
2/3 cup (140 grams) firmly packed light brown sugar
1/3 cup (80 ml) light corn syrup
1 1/2 teaspoons pure vanilla extract
1 1/2 teaspoons kosher salt
1 tablespoon (13 grams) butter, diced