1/4 cup unsweetened cocoa powder, plus more for sprinkling
1/3 cup all-purpose flour
1/4 tsp. salt
4 large eggs
1/2 cup granulated sugar
Butter for greasing pan
1 cup marshmallow creme
3/4 cup butter, softened
1 tsp. peppermint extract
1 1/2 cups powdered sugar
For the Marshmallow Creme:
3 large egg whites
1/2 tsp. cream of tartar
2 Tbsp. granulated sugar
3/4 cup golden corn syrup
2/3 cup granulated sugar
1/2 tsp. peppermint extract
4 ounces bittersweet chocolate chips or chopped
1/2 cup heavy cream
1 Tbsp. milk
Preheat the oven to 425ºF. Place a piece of parchment paper or a silicone mat on a 17x12 sheet pan and rub butter on it to grease.
In a large bowl combine the cocoa powder, flour, and salt.
Bring an inch of water to a simmer in a medium saucepan. Combine the eggs and sugar in a heatproof glass bowl, then place it over the simmering water (make sure the water doesn’t touch the bowl). Using a hand mixer, beat the eggs and sugar together over medium speed for about two minutes, until the eggs are thick, pale yellow, and warm to the touch. (If you have a thermometer, you want the eggs to be about 120º F. If you don’t have a thermometer, just touch the mixture with your finger every once in a while until it feels like hot tap water.) Remove the egg bowl from the heat and continue beating at medium high speed for another three minutes, until it’s thick and airy, and has reached the ribbon stage. That means when you drag and drizzle a spoonful of the liquid, it shouldn’t settle back into the liquid for a good 5-10 seconds. Mix in the melted butter.
Add the dry ingredients to the egg mixture, and gently fold it into the eggs with a spatula, working quickly. Spread the batter onto the buttered parchment or silicone mat, leaving an inch from the edges. Bake the cake for 5-6 minutes, until springy to the touch.
Place a piece of parchment paper on a flat surface and sprinkle lightly with cocoa powder. Flip the baked cake onto the parchment, then remove the parchment or silicone mat that the cake baked on. Gently roll the cake up, with the parchment paper, into a log while it’s still warm. This is like muscle memory for the cake, and it will roll easier again later. Rolling it up with the parchment paper keeps the layers from sticking to each other.
To make the marshmallow creme:
Start with the whisk attachment on your mixer and beat the egg whites and cream of tartar until foamy. Add the powdered sugar and beat until soft peaks form, set aside.
Meanwhile, in a saucepan, add 1/3 cup water, 3/4 cup corn syrup, and 2/3 cup sugar.
Cook over medium heat, while stirring it until the mixture reaches firm ball stage (instructions below) or 248 º on a candy thermometer. This step will take about fifteen minutes.
Once the corn syrup mixture has reached firm ball stage, turn the mixer onto medium and in a slow steady stream, pour the corn syrup mixture into the beaten egg whites.
Once all of the corn syrup mixture has been added, beat on high for 5 minutes.
Add peppermint extract and beat on high 1 minute.
Store in a tightly sealed container.
To make the peppermint filling:
In a large bowl, beat marshmallow creme, softened butter and peppermint extract with an electric mixer on medium speed until smooth, scraping bowl occasionally. On low speed, beat in 1/1/2 cups powdered sugar until smooth and creamy.
To assemble the swiss roll, carefully unroll the cooled cake. Allow narrow end to remain slightly curled. Drop 1 cup of the filling by spoonfuls over the cake, and spread evenly to within 1/2 inch of the edges. Reroll filled cake, using kitchen towel to help roll it up.
To make the Ganache:
To make the chocolate ganache, microwave the cream and chocolate in a heatproof bowl in 30-second intervals, stirring after each time, until combined. Add the milk, which will give a more pourable consistency. Pour the chocolate ganache evenly over the cake, then refrigerate for 20 minutes before serving, so the ganache can firm up.