La Buche - Christmas Log

• Genoise/ Sponge cake
• 6 egg yolks
• 170 grams of sugar (about 14 tablespoons)
• 6 egg whites
• 90 grams of all-purpose flour (about 3/4 cup)
• 30 grams of butter (2 tablespoons), melted & cooled
• Creme au beurre/ Coffee butter cream
• 1 cup of sugar
• 6 egg yolks
• 3/4 cup of warm milk (2%)
• 350 grams of cold butter (that's a little over 3 sticks of butter); cut into small pieces
• 1 teaspoon of instant coffee dissolved in a little bit of water
• 1 pinch of cornstarch
• 2 ounces of bittersweet chocolate (for the Chocolate butter cream part)

1. Preheat the oven to 400-425F (depending on the oven type). Butter a baking sheet 18" x 13" x 1.5" high & line with parchment paper.
2. In a mixer (use the K whisk extension if using a stand mixer) beat the egg yolks & sugar until light & fluffy, about 30 minutes (really that long!).
3. In a separate bowl beat the egg whites until stiff peaks form. Incorporate them delicately to the yolk & sugar mixture; fold in about 1/3 of the egg whites first, then alternate between adding small amounts the egg whites & the flour, folding ever so gently.
4. Add the melted butter - which should no longer be warm & pour onto the baking sheet spreading evenly.
5. Place in the oven for 18 to 20 minutes or until the cake is golden or until the edges pull back and the center of the cake springs back when touched. Watch it carefully!
6. Take the cake out of the pan and place it on a working surface and roll it up (as a 13? long log) with a moist kitchen towel inside so the cake doesn't dry out and the sponge cake takes the shape of the log.
7. Beat the egg yolks & the sugar until pale and fluffy, 10 minutes, add the instant coffee & a pinch of cornstarch. Then add the warm milk little by little, so as not to curdle the mixture.
8. Transfer the mixture to a pan and over medium-low heat, keep stirring until the mixture thickens, never letting it come to a boil. Test it with a wooden spoon: if the mixture coats the back of a wooden spoon it is ready.
9. Once thick enough, take off the heat and keep beating it until the mixture is less hot (slightly warmer than room temperature).
10. Put the cream back into the stand mixer and add the butter one little piece at a time, as you would for a mayonnaise. The cream will thicken little by little.
11. To assemble the "buche":rnrnUnroll the cake and place a thick layer of butter cream and roll it back up. Then put butter cream all over the exterior of the cake. To make the "buche" more log-like, with a fork add "lines" of chocolate butter cream (below) all around the log. Place on a serving platter and decorate with currants or meringue kisses or chocolates!
12. For the chocolate butter cream:rnrn2 ounces of bittersweet chocolate & the leftover butter cream (see recipe above)rnMelt the chocolate, cool & combine with the leftover butter cream.

cake, egg yolks, sugar, egg whites, flour, butter, butter cream, sugar, egg yolks, milk, cold butter, coffee, cornstarch, bittersweet chocolate

Taken from food52.com/recipes/2308-la-buche-christmas-log (may not work)