Bûche De Noël (Yule Log Cake)

Preheat oven to 350°. Line a 15" x 10" jelly roll pan with parchment. Grease parchment with cooking spray. Into a medium bowl, sift flour, cocoa powder, and salt.

In the large bowl of a stand mixer fitted with the whisk attachment, beat egg yolks on medium-high speed until thickened. Slowly add 1/2 c. granulated sugar and beat until pale and fluffy, 2 to 3 minutes. Slowly add dry ingredients and beat on medium-low speed until combined.

In another large bowl, using a handheld mixer on medium-high speed or a whisk, beat egg whites until soft peaks form. Add remaining 1/4 c. granulated sugar a little at a time and continue to beat until stiff peaks form. Working in batches, gently fold egg whites into batter with a spatula until just combined. Pour batter into prepared pan and spread in an even layer.

Bake cake until top springs back when lightly pressed, about 12 minutes.

Dust a clean kitchen towel with confectioners' sugar. Invert warm cake onto towel. Peel off parchment.

Starting at the short end and using the towel, tightly roll cake into a log. Let cool.

If you're using gelatin, in a small heatproof bowl, sprinkle gelatin over 2 Tbsp. cold water. Let bloom 5 to 10 minutes. Microwave until gelatin is runny, about 10 seconds—do not overheat!

In the large bowl of stand mixer fitted with the whisk attachment, beat cream, confectioners' sugar, vanilla, and salt until medium peaks form. Strain gelatin through a fine-mesh sieve. With the motor running, stream gelatin into whipped cream and beat until combined. Refrigerate until ready to use.

When cake is cool, unroll and evenly spread filling over cake. Using towel, tightly roll cake back into a log. Arrange seam side down on a baking sheet and refrigerate until well chilled, at least 1 hour and up to 1 day.

In the large bowl of stand mixer fitted with the whisk attachment, beat butter on medium-high speed until smooth. Add confectioners' sugar and cocoa powder and beat until no lumps remain. Beat in cream, vanilla, and salt.

When ready to serve, trim ends and frost cake with buttercream. Lightly dust with confectioners' sugar. Top with chocolate curls. Place cranberries and rosemary on log to create mistletoe.