Ingredients
Chestnut Chocolate Mousse
- 300 grams (10.4 ounces, about 2 cups) chestnuts, roasted and peeled (vacuum-packed, steamed or whole roasted in jar)
- 500 mL (2 cups) whole milk
- 100 grams (½ cup) granulated sugar
- 1 Tablespoon vanilla extract
- ½ teaspoon kosher salt, smoked (substitute kosher salt if unavailable)
- 113 grams (4 ounces, ⅔ cup chopped) dark chocolate (72% cocoa), finely chopped
- 500 mL (2 cups) heavy whipping cream, chilled
Chocolate Cake
- 180 grams (1½ cups) all purpose flour
- 60 grams (½ cup) rye flour, finely milled (substitute all purpose flour if unavailable)
- 1 teaspoon baking soda
- 1 teaspoon kosher salt, smoked (substitute kosher salt if unavailable)
- 177 mL (¾ cup) extra virgin olive oil
- 300 grams (1½ cups) granulated sugar
- 35 grams (⅓ cup) Dutch process cocoa powder, sifted
- 250 mL (1 cup) hot coffee
- 2 large eggs
- 120 grams (½ cup) full fat sour cream
- 1½ teaspoons vanilla extract
Chocolate Ganache
- 165 mL (⅔ cup) heavy whipping cream
- 113 grams (4 ounces, ⅔ cup chopped) dark chocolate (72% cocoa), finely chopped
- Chocolate baking pearls or chocolate shavings for garnish
Instructions
- Prepare the Chestnut Chocolate Mousse: Break the roasted chestnuts into small pieces and place in a 3-quart saucepan with milk, sugar, vanilla extract, and smoked kosher salt. Bring to a boil, reduce heat and simmer for 15-20 minutes until chestnuts soften and liquid is reduced by about a quarter. Let cool 5-10 minutes.
- Blend Chestnut Mixture: Transfer mixture to a blender and puree until silky smooth. Add finely chopped dark chocolate and blend until fully incorporated, scraping sides as needed. Pour into a bowl and whisk occasionally until cooled to room temperature.
- Whip Cream and Fold: Whip chilled heavy cream to medium peaks using a stand mixer. Fold one-third of the whipped cream into the chestnut chocolate mixture gently, then fold in the remaining two-thirds without overmixing. Cover with plastic wrap and chill at least 2 hours.
- Prepare the Chocolate Cake Batter: Preheat oven to 325°F (165°C, Gas Mark 3). Line a rimmed half sheet baking pan (18x13x1 inches) with parchment paper, extending edges for removal; do not grease. In a medium bowl, whisk together all-purpose flour, rye flour, baking soda, and smoked kosher salt.
- Mix Wet Ingredients: In a large bowl, whisk olive oil, sugar, cocoa powder, and hot coffee. Add eggs one at a time, whisking well after each. Add dry ingredients and whisk until smooth, then stir in sour cream and vanilla extract. Batter will be thin.
- Bake the Cake: Pour batter into prepared pan and tap firmly to remove air bubbles. Bake 15-18 minutes until toothpick comes out clean and center springs back. Cool in pan 15 minutes. Loosen edges with a knife, then lift cake using parchment to a cooling rack. Once cool, invert cake onto a cutting board and remove parchment.
- Assemble the Cake Layers: Spread chestnut chocolate mousse evenly over cooled cake with an offset spatula. Refrigerate to firm mousse. Trim about ½ inch off each side for even edges. Mark and cut cake into four equal rectangles. Layer each mousse-topped cake piece on a serving platter, stacking carefully. Chill in fridge while preparing ganache.
- Make the Chocolate Ganache: Heat heavy cream in a pot until nearly simmering. Remove from heat and add finely chopped dark chocolate. Let sit 1 minute, then whisk gently until smooth and lump-free.
- Finish the Cake: Pour ganache over the top layer of the stacked cake and spread to edges without allowing it to drip down sides. Garnish with chocolate baking pearls or shavings. Refrigerate cake until serving. Cake slices best when mousse is firm.
Notes
- Use smoked kosher salt for a subtle smoky flavor, but regular kosher salt works well as a substitute.
- Firmly chill mousse before assembling for clean layer formation and stability.
- Trim cake edges carefully to create neat rectangular layers for stacking.
- Use parchment paper with overhang to easily remove cake from pan without greasing.
- Slice cake with a long, sharp knife wiped clean between cuts for precise portions.
- Keep finished cake refrigerated to maintain mousse firmness and ganache consistency.
- Prep Time: 40 minutes
- Cook Time: 20 minutes
- Category: Dessert
- Method: Baking
- Cuisine: French
