2 envelopes unflavored gelatin, powdered
1/2 cup plus 1/3 cup cold water
1 cup sugar
1/3 cup light corn syrup
4 large egg whites
Pinch of salt
2 tsps. vanilla extract
1½ cups cornstarch, plus more for dusting
1½ cups powdered sugar
1 1/4 lbs. pounds 70% Scharffen Berger Cacao Bittersweet or 62% Scharffen Berger Cacao Semisweet Chocolate, chopped
1 1/2 cups roasted, unsalted peanuts or almonds, toasted
1/2 cup roasted Scharffen Berger Cacao Nibs (optional)
In a small bowl, sprinkle the gelatin over the 1/2 cup cold water to dissolve and soften. Set aside.
In a small saucepan fitted with a candy thermometer, mix the sugar and corn syrup with 1/3 cup of water. Place over medium-high heat.
In the bowl of an electric mixer, pour in the egg whites and beat on low speed until frothy. Add the pinch of salt.
When the syrup reaches between 210°F and 220°F, increase the speed of the mixer and beat the egg whites until they are thick and fluffy but do not overbeat.
When the syrup reaches 245°F, as the mixer is whipping, slowly pour the syrup into the egg whites, pouring so that the syrup does not fall on the whisk, which can cause it to splatter and stick to the sides of the bowl. (You will use this saucepan again to melt the gelatin, so don’t wash it yet.)
Scrape the gelatin and water into the pan that you used for the syrup and swirl it to dissolve (it should be hot enough to dissolve the gelatin). Pour the liquefied gelatin into the egg whites as they are whipping. Add the vanilla and continue to whip for 5 minutes, or until the mixture comes to room temperature.
Mix the cornstarch and powdered sugar together. Using a sifter, dust an 11- x 17-inch (approximately) baking sheet evenly and completely with cornstarch/sugar mixture. Use a spatula to spread the marshmallow mixture into a layer on the pan. Set the sheet aside to dry for at least 4 hours, or preferable overnight, uncovered.
Using a pizza cutter or scissors dusted with the powdered sugar and cornstarch mixture, cut the marshmallows into any size or shape pieces. Toss the pieces in remaining sugar and cornstarch mixture. Working in small batches, place the marshmallows in a wire strainer and shake vigorously until the excess sugar and cornstarch mixture falls away.
Cover a baking sheet with plastic wrap, parchment, or waxed paper.
Chop up all the chocolate. Place 16 ounces of the chocolate in a heatproof bowl and melt it over simmering water, stirring frequently, until it is fully melted and smooth.
Remove the bowl from over the simmering water and stir in the remaining 4 ounces of chocolate. Let stand, stirring occasionally, until the temperature falls to the low 80°F range.
“Flash” the bowl over the simmering water by putting it back over the water for 3 to 5 seconds at a time, stirring frequently, until the temperature reads between 88° F and 91°F (using care if using a breakable glass thermometer). You’ll need to flash it several times to get it to the correct temperature. Don’t be tempted to keep the chocolate over the heat until it reaches the proper temperature; it will continue to rise after you remove the bowl from the heat. (If the temperature rises over 91°F, you’ll need to begin the process all over again.)
Test the chocolate by spreading a thin layer on waxed paper, aluminum foil or a plate. Let it cool for a few minutes. If it hardens within that period of time, it is tempered. If it stays wet or gets grainy, then it is not properly tempered.
Once you have tempered the chocolate, immediately toss the marshmallows, nuts and cacao nibs into the tempered chocolate until just coated, stirring as little as possible because the chocolate cools as it is stirred and will set up quickly.
Heap the Rocky Road on the lined baking sheet, spread just a bit, and then chill until firm.
Cut the Rocky Road into irregular pieces and serve.
The candy can be stored at room temperature in an airtight container for up to 2 weeks (although you will not be able to keep it around for more than a day or so).