*You can substitute regular cocoa powder. A darker, more intense cocoa powder delivers more chocolate flavor.
1. LINE a 9 x 5-inch loaf pan with parchment paper or foil. Spray with cooking spray.
2. COMBINE the granulated sugar, corn syrup, salt and 2 tablespoons of the water in a medium sauce pan. Clip on a candy thermometer, and turn the heat to medium-high. Bring the mixture to a boil without stirring and continue to cook until it reaches 238°F. Meanwhile…
3. PLACE another 2 tablespoons of the water in a medium bowl, and sprinkle the gelatin on top. Let sit to dissolve for 5 minutes.
4. ADD the last 2 tablespoons of water to a small dish and microwave for 25 seconds, until hot. Remove from the microwave carefully, and whisk in the cocoa powder. Stir the cocoa powder mixture into the dissolved gelatin.
5. SLOWLY STREAM the hot sugar (238°F) into the gelatin mixture while continuously beating with a hand mixer on medium-high. Be careful not to pour the hot sugar near the sides of the bowl because it will stick and harden immediately. Beat the mixture for 10 minutes, until light and fluffy; then beat in the vanilla.
6. POUR the mixture into the loaf pan, and let set for at least 3 hours. Then lift the parchment paper or foil out of the pan, and cut the marshmallows into squares with a well-greased knife. Grease the knife between each cut. If the marshmallows are too sticky, roll them in extra cocoa powder.
7. DIP the marshmallows: First place the marshmallows in the freezer for 5 minutes, on a baking sheet. While they are chilling, combine the chocolate chips and coconut oil in a small microwave-safe bowl. Microwave on medium heat in 30-second pulses until melted, stirring between each pulse. Stir until chocolate is evenly melted and smooth.
8. REMOVE the marshmallows from the freezer and dunk half of each marshmallow in the melted chocolate. Place each marshmallow back on the sheet, and refrigerate until the chocolate sets, about 5 minutes.