Potato Flake Sourdough Yule Log (Bûche de Noël)
This potato flake sourdough yule log (Bûche de Noël) is a festive, fermented twist on a classic Christmas dessert!
Equipment
- Sheet Pan (18x13-inch)
- Stand Mixer or Hand Mixer
- Large mixing bowl
- Fine Mesh Strainer or Sifter
- Parchment Paper
- Clean Kitchen Towel
- Spatula or Offset Spatula
- Plastic wrap
Ingredients
Chocolate Cake
- 1 1/4 cups all-purpose flour 188 grams
- ½ teaspoon instant coffee powder
- 3 Tablespoons unsweetened cocoa powder 22 grams
- 1 ¼ cups sugar 276 grams
- ¼ cup potato flake sourdough starter
- 6 eggs about 50 g each
- 1 teaspoon vanilla extract
- ½ cup powdered sugar for dusting towel
After fermentation:
- ¾ teaspoon baking soda
- ½ teaspoon salt
Whipped Cream Filling
- 2 cups heavy cream
- ½ cup powdered sugar
- 1 teaspoon vanilla
Whipped Chocolate Buttercream
- 1 cup unsalted butter softened
- 3 cups powdered sugar
- ½ cup cocoa powder
- ¼ cup heavy cream
- 1 Tablespoon instant coffee
- ¼ teaspoon salt omit if using salted butter
Instructions
- In a large bowl, whisk together the flour, instant coffee, and cocoa powder. Add the sugar, potato flake starter, vanilla, and eggs. Using a hand mixer, blend until just combined.
- Scrape down the sides of the bowl to make sure everything is fully incorporated. Cover tightly with plastic wrap and let the batter ferment at room temperature for 8–12 hours.
- After fermentation, preheat your oven to 375°F. Spray your 18x13" sheet pan, line with parchment paper, and spray the parchment too.
- Sift the baking soda and salt evenly over the fermented batter using a fine mesh strainer. Gently mix until fully combined.
- Pour the batter onto your prepared sheet pan and spread it evenly. Bake for 12–15 minutes, or until the top springs back when gently pressed. Don’t overbake — that’s the #1 cause of cracking when rolling.
- Before the cake comes out of the oven, lay out a clean kitchen towel and dust it generously with powdered sugar.
- As soon as the cake is done, immediately flip it onto the sugar-dusted towel. Slowly peel off the parchment paper.
- Starting from one long side, roll the cake up in the towel. Place seam-side down to let the cake cool fully. Doing this is the best way to "train" the cake to roll neatly later. If you roll from the short end you will get more of a swirl, but you may not have a log that is long enough to cut and position into a branch.
- Make the Whipped Cream Filling: In a stand mixer with the whisk attachment (or using handheld mixer), whip the heavy cream, powdered sugar, and vanilla. Start on low, then increase to high speed until you reach thick, sturdy, Cool-Whip-like peaks. Avoid over-beating — stop as soon as it becomes pillowy and holds its shape.
- Once the cake is completely cool, unroll it gently. Spread the whipped cream filling all the way to the edges.
- Re-roll the cake, this time without the towel. Some of the whipped topping will be coming out. That is okay, it will be the side that is on the bottom when we are done. Wrap in plastic wrap and refrigerate at least 2 hours (or overnight). This chill time helps the cake set so it slices beautifully.
- Make the Whipped Chocolate Buttercream: Right before decorating, beat the softened butter for 3 minutes until creamy and pale.
- Add powdered sugar, cocoa powder, heavy cream, instant coffee, and salt. Mix on low until combined, then beat on high for another 3 minutes, scraping halfway through. The frosting should be very fluffy and smooth.
- Time to Decorate Your Yule Log: Slice off about ⅓ of the cake at an angle. Place this smaller piece against the side of the larger log to make a “branch.” Frost the entire cake with your whipped chocolate buttercream. Use a fork to create subtle bark-like texture.
- Garnish with fresh rosemary or tarragon, and a few fresh cranberries. Finish with a dusting of powdered sugar for “snow.”
Notes
Be sure to see the full blog post for photos for the best understanding of assembling and decoration.