INSTRUCTIONS
Chocolate Ganache

1. Add cream and honey to a small pot. Bring to a gentle boil over medium heat, about 3 to 5 minutes.
2. Remove the pot from heat, then add chocolate and butter. Set aside without stirring for 3 minutes to melt. Stir until very smooth and shiny.
3. Transfer ganache to a bowl and refrigerate, stirring occasionally, until fully cooled and thickened but not solid, about 30 minutes to 1 hour. Cover and refrigerate up to 5 days ahead.

Chocolate Sponge

1. Preheat oven to 350°F. Meanwhile, lightly grease a 10-in x 15-in jelly roll pan. Cut a 12-in x 16-in piece of parchment. Trim away a 1-inch square from each corner. Line greased pan with prepared parchment, pressing the paper into the corners and up sides of pan. Trim away any overlapping paper.
2. Add egg whites and salt to a large bowl. Beat with an electric mixer at medium speed until soft peaks form, about 2 to 3 minutes. While beating, gradually add ¼ cup sugar. Continue to beat until shiny and stiff peaks form, approximately 2 to 3 minutes. Do not overbeat. Set aside. No need to wash beaters for beating egg yolks.
3. Add yolks and remaining ½ cup sugar to another large bowl. Beat with an electric mixer at medium speed until pale and very thick, about 3 to 4 minutes. Beat in vanilla. Set a fine mesh sieve over top. Add cocoa and flour, then sift over yolks. Fold gently with a stiff spatula until combined.
4. Add a third of meringue to yolk-cocoa mixture. Fold gently until combined with a few streaks remaining. Continue with remaining thirds of meringue, folding gently just until no streaks remain.
5. With the edge of bowl close to prepared pan, gently transfer batter into pan. Smooth top. Bake in middle of oven until batter is set and a toothpick inserted into the center of the cake comes out clean, approximately 10 to 13 minutes.
6. While sponge bakes, cut another 12-in X 16-in piece of parchment paper. This second piece will be for rolling the baked sponge into shape. Place parchment on a large work surface with the short end closest to you. Add about 2 tbsp cocoa to a small fine mesh sieve. Set aside.
7. When sponge is done, place pan on a cooling rack. Run a knife around edges of pan. Lightly dust top of sponge with some cocoa. Place second piece of parchment over top. With oven gloves, invert onto work surface, parchment-side down. Peel baked parchment away from sponge, then discard. Lightly dust bottom of sponge with some more cocoa.
8. Starting at short end closest to you, tightly roll sponge in parchment away from you into a tight log. Transfer sponge rolled in parchment back to rack, seam side down. Cool completely, approximately 45 minutes to 1 hour. Cooled sponge, still in parchment, can be wrapped tightly in plastic, then kept at room temperature for up to 1 day.

Whipped Mascarpone Filling

1. Add mascarpone, cream and sugar to a large bowl. Beat with an electric mixer at low speed until combined, about 1 minute. Increase speed to medium-high until thick and fluffy, approximately 3 to 4 minutes. Beat in rum, vanilla and vanilla bean seeds, if using. Cover and refrigerate until ready to assemble cake, up to 1 day ahead.

To Assemble:

1. Gently unroll sponge. Spread whipped mascarpone evenly onto sponge, leaving 1-in seam end uncoated. Roll sponge around filling, starting at the tightly curled end, to form a tight log. Carefully transfer to serving platter.
2. Trim a small section off one end at an angle. Arrange end piece next to log, cut-side in, to create a “branch”.
3. Spread cooled ganache evenly over top, sides and ends of cake. If desired, decorate ganache with tines of a fork to create the texture of tree bark.
4. Serve immediately or refrigerate up to 2 days.