Chocolate Ganache and Marshmallow Topping
FOR THE GANACHE, HEAT:
FOR THE MARSHMALLOW TOPPING, SPRINKLE:
Prepare the ganache first, then whip up the marshmallow topping while the ganache sets up.
For the ganache, heat cream and corn syrup in a saucepan over medium until simmering. Pour cream over chocolate in a bowl; let stand 5 minutes, then whisk until smooth. Let ganache stand until thickened, 45 minutes to 1 hour.
For the marshmallow topping, sprinkle gelatin over cold water in the bowl of a stand mixer.
Boil sugar, corn syrup, ¼ cup water, and salt in a saucepan over medium-high heat until mixture reaches 240° on a candy thermometer, about 10 minutes; immediately remove from heat.
Slowly drizzle syrup down side of mixer bowl into gelatin mixture, mixing with whisk attachment on low speed. Once all syrup is added, gradually increase speed to high.
Whip mixture until billowy and lukewarm, about 6 minutes.
Add vanilla to mixture during last minute of whipping.
The ganache starts out thin, but will thicken to a more spreadable consistency once cooled.
The gelatin will quickly solidify in the water. That's okay. It will melt as you mix in the sugar syrup.
To prevent sugar bits, slowly drizzle syrup down the side of the mixer bowl with the machine running.
When the topping thickens, turns pure white, becomes fluffy, and forms peaks, it's ready.
Because the marshmallow topping is thick and sets up quickly, piping is the easiest way to apply it.