Chocolate Mocha Cake
Recipe from Tartelette
Chocolate Mocha Cake:
Serves 8-10 (Makes 2 medium or one long)
For the cake:
1 stick butter
2 tsp instant coffee
3/4 cup water
100 gr. chocolate
1 cup sugar
1 egg
1 1/4 cup all purpose flour
1 tsp baking powder
2 Tb cocoa powder
In a large saucepan set over low heat, stir together the butter, instant coffee, water, chocolate and sugar until smooth. Remove from the heat and let cool 10 minutes.
Whisk in the egg, flour, baking powder and cocoa powder until incorporated.
Line a baking sheet with parchment paper, lightly coat with cooking spray. Pour the chocolate cake batter in the baking sheet and bake for 15-20 minutes at 375F. Do not overbake or it will crack when you roll it. Check after 12-15 minutes, if it springs back when you touch it, it's done.
Remove from the heat, cover with a towel and let cool a few minutes.
Cover with a sheet of parchment paper and unmold on the kitchen counter. Peel the bottom parchment layer that is now your top, roll the cake without filling with the parchment paper from the long side to give it some form and elasticity for when you fill it with the buttercream. Let cool completely.

Mocha Buttercream:
6 large egg yolks
1 cup sugar
1/2 cup water
4 sticks of butter (don't roll your eyes, you won't feel it:))
Butter should be soft but nor mushy (65F)
1 Tb vanilla bean paste
2 Tb instant coffee dissolved in 1 Tb hot water
In a stand mixer or with a hand held one, whip the egg yolks for a minute.
Boil water and sugar until the temperature reaches 238F on a candy thermometer.
Slowly pour the hot sugar syrup over the egg yolks on a steady stream, continue beating the yolks until pale in color and cooled. Beat in the softened butter until the buttercream is smooth a
and together. Add the vanilla bean paste and the coffee, beat a few extra seconds until incorporated.

For the ganache:
300 gr milk chocolate
3/4 cup heavy cream
Bring the cream to a boil in a heavy saucepan. Pour over the chocolate. Let stand a couple of minutes and then stir carefully until it is incorporated and smooth.

To assemble:
Unroll the cake from the parchment paper, fill with the buttercream (you won't use it all). Reroll the cake, cut it in half (so it does not seem like a Yule log, but more like a Swiss roll). Set each half on a wire rack set over a piece of parchment paper. Cover with the ganache and douse with chocolate sprinkles. Refrigerate to set.