Hot Chocolate Layer Cake with Homemade Marshmallows
For the cake:
6 oz (3/4 cup) unsalted butter; more for the pans
13 ½ oz (3 cups) unbleached all-purpose flour; more for the pans
¾ cup canola oil
4 ½ oz bittersweet chocolate; finely chopped (I used chocolate chips)
3 cups white sugar
2 ¼ oz (3/4 cup) natural unsweetened cocoa powder (If you use Dutch cocoa powder, don’t use any baking soda. Use baking powder instead and double what it should have been for the soda. i.e. 1 tsp baking soda = 2 tsp baking powder instead)
3 large eggs, at room temperature
¾ cup buttermilk, at room temperature
2 Tbs. vanilla extract
2 ½ tsp baking soda
½ tsp. kosher salt
For the frosting:
2 ½ cups heavy cream
3 oz (6 Tbs) unsalted butter
2 tsp vanilla extract (originally called for 1 vanilla bean, split lengthwise and seeds scraped out)
6 oz bittersweet chocolate, finely chopped (I used chocolate chips)
2 cups white sugar
6 oz cocoa powder
½ cup corn syrup
¼ tsp kosher salt
Position racks in the bottom and top thirds of the oven and heat the oven to 350 F.
Butter three 9x2” round cake pans (springform works best) and line each with a parchment round. Butter the parchment, then dust with flour and knock out the excess.
In a 3 quart saucepan, combine the butter, oil, chopped chocolate and 1 cup water. Heat over medium heat until melted.
In a large bowl, whisk the flour, sugar and cocoa powder. Pour the hot chocolate mixture into the sugar mixture and whisk until combined.
Whisk in the eggs, one at a time, then whisk in the buttermilk, vanilla, baking soda(powder), and salt. Divide the batter evenly among the prepared pans.
Set two pans on the top rack and the third on the lower rack. Stagger the pans on the oven racks so that no pan is directly over another. Bake, swapping and rotating the pans’ positions after 20 minutes, until a toothpick inserted in the center of each cake comes out clean, 35-40 minutes. Cook on racks for 10 minutes. Invert the cakes onto the racks, remove the parchment paper and cool completely.
Make the Frosting:
In a 4 quart saucepan over low heat, combine the cream, butter and vanilla and stir until the butter is melted. Whisk in the chopped chocolate until melted (completely melted! Don’t leave any little tiny chunks). Whisk in the sugar, cocoa powder, syrup, and salt until smooth. Be sure the cocoa powder dissolves completely. Pour into a 9x13 pan and freeze until firm (about 2 hours) or refrigerate overnight.
Remove the frosting from the fridge or freezer. Transfer to the bowl of a stand mixer fitted with the paddle attachment and beat on medium for 2 minutes to soften. Change to a whisk attachment and beat at medium-high speed until light and fluffy, about 3 minutes.
Homemade Marshmallows:
Gelatin 1 1/4 oz
Cold Water 16 fl oz
Sugar 1 lb 8 oz
Corn Syrup 12 oz
Honey 8 oz
Vanilla 1/2 fl oz
1. Line a half sheet pan with parchment paper.
2. Bloom the gelatin in 8 oz water. (Blooming is when you add the gelatin to water and wait until it absorbs it all and becomes a big blob)
3. Meanwhile, combine the sugar, corn syrup, honey and remaining 8 oz water in a heavy bottom saucepan. Stir to ensure all the sugar is moistened. Bring to a boil over high head stirring to dissolve the sugar. Stop stirring and skim the surface of the syrup to remove any impurities. Continue to cook without stirring, occasionally washing down the sides of the pan using a wet pastry brush. Heat to 252 degrees. Remove from heat, cool to approx. 210 degrees.
4. While the sugar is cooling, dissolve the gelatin over simmering water (using a double boiler, put a metal or glass bowl over a pan of boiling water, but do not let the bottom of the bowl touch the water). Remove from heat and stir in vanilla.
5. Stir the gelatin into the cooled sugar syrup using the whip attachment on high speed until medium peaks form.
6. Spread the mixture evenly in the prepared sheet pan, the easiest way to do this is to place the mixture in the frame, place a sheet of oiled parchment on top of the marshmallow mixture and roll the marshmallow into the pan.
7. Remove the slab from the pan, inverting onto work surface and peel off the paper.
8. Cut the marshmallows and coat in 1/2 powdered sugar and 1/2 cornstarch.
Make the marshmallows. (Adrienne made some for her cake so I just used her leftovers). I'm sure you could use store bought as well, but it won't be quite as cool.
Assemble cake.
Here is my finished cake with the homemade marshmallows piled on top and dusted with some dutch cocoa powder!
It took me all day long, but I was so proud of my cake and really excited for Mart to see it and taste it. He loved it and it was by far the best birthday cake I have ever made.
