-
Spray a 13-by-9-inch baking pan with cooking spray, then line the pan with parchment paper, leaving a few inches of overhang on each side. Set aside.
-
Place egg white in the base of a stand mixer fitted with the whisk attachment. Spray a rubber spatula with cooking spray and set aside.
-
Combine sugar, corn syrup, and water in a small saucepan fitted with a candy thermometer and place over medium-high heat. Stir mixture until sugar completely dissolves.
-
Once sugar mixture is at 270°F, add salt to egg white and beat at high speed to stiff peaks, about 2 minutes.
-
Once sugar mixture reaches 275°F, remove from heat. Keeping the mixer on high speed, very slowly pour 1 tablespoon of the hot syrup in a thin stream down the side of the bowl (avoiding the whisk) and let it completely incorporate before adding more. Repeat until you’ve added all the syrup; it should take about 2 minutes. Continue to mix until nougat pulls away from the sides of the bowl, about 1 minute more. Turn off the mixer and, using the oiled spatula, stir in peanut butter; mixture should be thick and spongy.
-
Immediately turn nougat into the prepared pan and, using the oiled spatula or your hands, spread mixture evenly. Let sit uncovered while you make the caramel, at least 5 minutes.