01 -
Line an 8-inch square baking pan with parchment paper, leaving overhang on two sides for lifting the fudge out later.
02 -
Add the white baking chips, sweetened condensed milk, and 2 1/2 tablespoons heavy cream to a microwave-safe bowl. Microwave in 30-second bursts, stirring after each one, until smooth.
03 -
Stir in the vanilla and fine sea salt until the fudge base looks thick, glossy, and evenly mixed.
04 -
Place the unwrapped caramels and 1 1/2 tablespoons heavy cream in a second microwave-safe bowl. Microwave in 30-second bursts, stirring until thick and pourable.
05 -
Fold about three quarters of the caramel into the white chocolate mixture 3 or 4 times, leaving visible streaks. Spread into the pan, dollop the remaining caramel on top, and swirl with a knife.
06 -
Refrigerate for at least 4 hours, or until firm in the center. Lift out by the parchment and cut into 25 small squares. Sprinkle with flaky salt if using.