Line a 9x13-inch pan with parchment paper, letting it overhang the sides, then butter the parchment.

In a heavy-bottomed saucepan, combine the sugar, corn syrup, honey, and water over medium heat. Stir just until the sugar dissolves, then stop stirring.

Clip on a candy thermometer and cook the syrup undisturbed until it reaches 265°F, about 12–18 minutes.

While the syrup cooks, whip the egg whites with the salt in a stand mixer on medium speed until soft peaks form.

Once the syrup hits 265°F, with the mixer running on low, pour the hot syrup down the side of the bowl in a slow, steady stream.

Add the vanilla, then increase the mixer speed to medium-high and whip for 6–8 minutes, until thick and glossy.

Fold in the roasted peanuts by hand with a sturdy spatula, working quickly.

Press the nougat evenly into the prepared pan using a buttered spatula or buttered hands.

Let cool at room temperature for at least 3 hours, until completely firm.

Lift the nougat out using the parchment overhang, cut into bars with a hot, dry knife, and wrap individually.