How to Make It
Preheat the oven to 200°. Spread the almonds and pistachios on a large baking sheet and keep warm in the oven. Line an 8-inch square baking pan with parchment paper, allowing the paper to hang over on two opposite sides. Lightly spray the paper with vegetable oil spray. In a bowl, combine the cornstarch and confectioners' sugar and dust the pan with half of the mixture.
In a medium saucepan, combine the 1 2/3 cups of granulated sugar with 1/4 cup of the honey and the water and bring to a boil. When the temperature of the syrup reaches 245° F on a candy thermometer, after 20 to 30 minutes, bring the remaining 1/2 cup of honey to a boil in a small saucepan. Continue cooking the sugar syrup.
Meanwhile, in the bowl of a standing electric mixer fitted with the whisk, beat the egg whites with the salt until firm peaks form. Add the remaining 1 tablespoon of granulated sugar; beat until combined.
When the pure honey reaches 265° F on a candy thermometer, after 5 to 8 minutes, add it in a fast, steady steam to the egg whites with the mixer at medium-high speed. When the sugar syrup reaches 305° F, add it to the egg whites in a fast, steady stream and beat at high speed until the mixture is pale, 3 to 5 minutes. Using an oiled wooden spoon, immediately stir in the hot nuts (the nougat will be a bit stiff).
Scrape the nougat into the prepared pan, and, using oiled hands, press it into an even layer. Dust the remaining cornstarch mixture on top, cover and let cool.
Lift the nougat from the pan and brush off the excess cornstarch powder. Using a serrated knife, cut the nougat into 3/4-inch slices. Cut the slices in pieces and serve, or wrap in wax paper and store in an airtight container for up to 2 weeks.