Quick Recipe Version (TL;DR)
Quick Ingredients
- 5 large eggs; 120 g (2/3 cup) sugar; 65 g (1/2 cup) cake flour; 25 g (1/4 cup) cocoa; 1 tsp vanilla; 1/4 tsp salt; 30 g (2 tbsp) melted butter
- 4 large egg whites (120 g); 240 g (1 1/4 cups) sugar; 340 g (3 sticks) unsalted butter; 2 tsp espresso powder + 1 tbsp hot water; 60 g (2 oz) dark chocolate, melted; 1 tsp vanilla; 1/4 tsp salt
- 225 g (8 oz) dark chocolate; 240 ml (1 cup) heavy cream; 14 g (1 tbsp) butter; pinch salt
- 2 large egg whites (70 g); 100 g (1/2 cup) sugar; 1/4 tsp cream of tartar; 1/2 tsp vanilla; 1 tsp cocoa; 30 g (1 oz) melted chocolate
- Powdered sugar for dusting; optional rosemary sprigs
Do This
- 1. Make meringue mushrooms: whip, pipe caps/stems, bake at 200°F (93°C) 75 minutes, dry 1 hour in the turned-off oven; glue with melted chocolate.
- 2. Heat oven to 375°F (190°C). Line a 10×15-inch jelly roll pan with parchment; prepare a clean towel dusted with powdered sugar.
- 3. Whip eggs + sugar to thick ribbon, fold in sifted flour/cocoa/salt, then butter and vanilla. Bake 10–12 minutes.
- 4. Invert hot cake onto sugared towel, peel parchment, roll up with towel; cool 30–40 minutes.
- 5. Make mocha Swiss meringue buttercream; add espresso and melted chocolate until silky.
- 6. Unroll, spread buttercream, re-roll; chill 20–30 minutes.
- 7. Make ganache; cool to spreadable. Frost log, texture like bark, add mushrooms, dust “snow.”
Why You’ll Love This Recipe
- Light-as-air chocolate sponge that rolls without cracking.
- Silky, not-too-sweet mocha Swiss meringue buttercream inside.
- Deep, glossy chocolate ganache “bark” that’s easy to texture.
- Cute, crisp meringue mushrooms and a snowy finish for festive flair.
Grocery List
- Produce: Optional fresh rosemary sprigs (for garnish)
- Dairy: Unsalted butter, heavy cream, eggs
- Pantry: Granulated sugar, powdered sugar, cake flour, unsweetened cocoa powder, dark chocolate, vanilla extract, espresso powder, cream of tartar, kosher salt, parchment paper
Full Ingredients
Chocolate Sponge Cake
- 5 large eggs, room temperature
- 120 g granulated sugar (2/3 cup)
- 65 g cake flour (1/2 cup), spooned and leveled
- 25 g unsweetened cocoa powder (1/4 cup), sifted
- 1/4 tsp kosher salt
- 1 tsp vanilla extract
- 30 g unsalted butter (2 tbsp), melted and cooled
- Powdered sugar, for dusting the towel
Mocha Swiss Meringue Buttercream
- 4 large egg whites (120 g)
- 240 g granulated sugar (1 1/4 cups)
- 340 g unsalted butter (3 sticks), room temperature and cubed
- 2 tsp espresso powder dissolved in 1 tbsp hot water
- 60 g dark chocolate (2 oz), melted and cooled to room temperature
- 1 tsp vanilla extract
- 1/4 tsp fine salt
Ganache “Bark”
- 225 g dark chocolate (8 oz), finely chopped
- 240 ml heavy cream (1 cup)
- 14 g unsalted butter (1 tbsp), optional for shine
- Pinch of salt
Meringue Mushrooms
- 2 large egg whites (70 g), room temperature
- 1/4 tsp cream of tartar
- 100 g granulated sugar (1/2 cup)
- 1/2 tsp vanilla extract
- 1 tsp unsweetened cocoa powder, for dusting
- 30 g dark chocolate (1 oz), melted (for “glue”)
Finishing
- Powdered sugar, for “snow”
- Optional fresh rosemary sprigs
Step-by-Step Instructions
Step 1: Make the meringue mushrooms (they can be made ahead)
Heat the oven to 200°F (93°C). Line 2 baking sheets with parchment. In a clean bowl, beat the egg whites and cream of tartar to soft peaks. Slowly stream in the sugar and continue whisking to glossy, stiff peaks, 5–7 minutes. Beat in vanilla. Transfer to a piping bag fitted with a round tip (or a zip-top bag with 1/2-inch corner snipped). Pipe mushroom caps as mounds (about 1 to 1 1/2 inches wide) and stems as tall cones. Dust caps lightly with cocoa. Bake 75 minutes, then turn the oven off and let meringues dry inside 60 minutes. Cool completely. Use melted chocolate to attach caps to stems; allow to set.
Step 2: Prep the pan and rolling towel
Heat the oven to 375°F (190°C). Line a 10×15-inch jelly roll pan with parchment, leaving a small overhang. Lightly mist or butter the parchment. Lay out a clean kitchen towel and generously dust it with powdered sugar to prevent sticking during the initial roll.
Step 3: Make the chocolate sponge
In a large bowl (stand mixer or hand mixer), beat the eggs and sugar on high until the mixture is pale, tripled in volume, and falls in thick ribbons, 6–8 minutes. In a separate bowl, sift together cake flour, cocoa, and salt. Sift the dry ingredients over the egg foam in 2 additions, gently folding with a wide spatula just until no streaks remain. Stir vanilla into the cooled melted butter, then fold a small scoop of batter into the butter to lighten it. Gently fold the butter mixture back into the batter. Spread evenly in the prepared pan and smooth the top. Bake 10–12 minutes, until the cake springs back and a toothpick comes out clean.
Step 4: Roll the cake while hot
Run a knife around the edges. Invert the hot cake onto the sugared towel and peel away the parchment. Dust the surface lightly with powdered sugar. Starting from a short end, roll the cake up with the towel inside. Set seam-side down and let cool until barely warm, 30–40 minutes. Rolling while warm “teaches” the cake its shape and prevents cracks later.
Step 5: Make the mocha Swiss meringue buttercream
Put egg whites and sugar in a clean, heatproof mixing bowl. Set over a pot of gently simmering water (do not let the bowl touch the water) and whisk constantly until the sugar dissolves and the mixture reaches 160°F (71°C), 3–5 minutes. Transfer to a mixer and whip on high until glossy, stiff, and cool to the touch, 8–10 minutes. With the mixer on medium, add the butter a few cubes at a time; the mixture may look curdled—keep beating until silky. Beat in vanilla, salt, dissolved espresso, and cooled melted chocolate.
Step 6: Fill and re-roll
Carefully unroll the cooled cake. Spread an even layer of mocha buttercream over the surface (use about 2 1/2 to 3 cups), leaving a 1/2-inch border on the far short edge. Roll up again (without the towel) from the short end toward the border; wipe away any squeeze-out. Wrap in parchment or plastic and chill 20–30 minutes to firm for frosting. Trim 1–2 inches from each end for neat slices. For a branch effect, cut a 3-inch piece on the diagonal and reserve.
Step 7: Make the ganache “bark”
Place chopped chocolate in a heatproof bowl. Heat cream to a gentle simmer; pour over the chocolate. Let sit 2 minutes, then stir in small circles until smooth. Stir in butter and a pinch of salt. Cool, stirring occasionally, until thickened to a spreadable, peanut-butter-like consistency, 20–30 minutes.
Step 8: Frost, texture, and decorate
Set the log on a serving board. If using the branch piece, attach it to the side with a dab of ganache. Frost the log with ganache, leaving the ends exposed to show the spiral. Create bark texture by dragging a fork or small offset spatula along the length and swirling knots. Arrange meringue mushrooms on and around the log, securing with dots of ganache. Tuck in a few rosemary sprigs if using. Dust lightly with powdered sugar for “snow.” Chill 15 minutes to set, then serve at cool room temperature.
Pro Tips
- Do not overbake the sponge; even 1–2 extra minutes can cause cracking. Pull it as soon as it springs back.
- If Swiss meringue buttercream looks soupy, it’s too warm—chill the bowl 10 minutes and whip again. If it looks curdled, keep whipping; it will emulsify.
- For the cleanest spiral, keep the buttercream layer thin and even, and leave a small unfrosted border on the final edge.
- Let ganache cool until thick before applying; too warm and it will drip instead of holding bark texture.
- Make mushrooms days ahead to spread out the work.
Variations
- Hazelnut Mocha: Fold 1/2 cup finely chopped toasted hazelnuts over the buttercream layer; finish with a sprinkle on the “forest floor.”
- Orange-Chocolate: Add 1 tbsp finely grated orange zest to the sponge and brush the cooled cake with 2–3 tbsp orange liqueur syrup before filling.
- Vanilla-Almond: Swap cocoa out of the sponge (use 90 g cake flour total), flavor buttercream with 1 tsp almond extract, and finish with white chocolate ganache bark.
Storage & Make-Ahead
Meringue mushrooms keep up to 1 week airtight at room temperature. The finished Bûche de Noël can be refrigerated up to 24 hours; bring to cool room temperature 30–45 minutes before serving. Leftovers keep 3 days covered in the fridge. Freeze the unfrosted rolled cake (well wrapped) up to 1 month; thaw overnight in the fridge. Swiss meringue buttercream can be refrigerated 1 week or frozen 2 months; bring to room temp and rewhip before using.
Nutrition (per serving)
Approximate values for 1 of 12 servings: 650 calories; 45 g fat; 56 g carbohydrates; 7 g protein; 220 mg sodium. Values will vary based on exact ingredients and garnish.
