- Non-stick cooking spray
- ⅓ c. plus ½ c. unsweetened cocoa powder (I used a mixture of black onyx cocoa powder and the regular kind)
- 3 (.25-oz) envelopes gelatin
- 1½ c. granulated sugar
- 1 c. corn syrup
- ½ c. confectioners’ sugar
- Line an 8-inch-square baking dish with foil, then coat inside with cooking spray.
- Whisk ⅓ cup cocoa powder with ⅓ cup hot water in a bowl until dissolved.
- Combine gelatin with ½ cup water in a separate large bowl; let stand 5 minutes. Beat cocoa mixture into gelatin mixture with an electric mixer on low speed until just combined.
- Combine granulated sugar, corn syrup, and ½ cup water in a saucepan. Cook over medium heat, stirring, until sugar dissolves. Increase heat to high and cook 8 minutes (do not stir). Remove saucepan from heat and immediately pour hot sugar mixture into gelatin mixture; beat on low speed until combined. Increase speed to high and beat until thick and fluffy, 10 minutes.
- Pour mixture into prepared baking dish, using fingers to smooth top. Combine ½ cup cocoa with confectioners’ sugar; sprinkle some cocoa mixture over top. Cover with plastic wrap and let stand at room temperature at least 6 hours.
- Put remaining cocoa mixture into a gallon-size Ziploc plastic bag or large bowl. Cut marshmallow into cubes and drop them into plastic bag or bowl; toss to coat with cocoa mixture. Store in Ziploc bag at room temperature.