Hot Chocolate Gianduja Cake Recipe

Prepare

Preheat the oven to 350°F (175°C). Grease and line the bottom of a 9-inch (23 cm) round cake pan with parchment; grease parchment as well.

In a large bowl, sift together the all-purpose flour, unsweetened cocoa powder, granulated sugar, baking powder, baking soda, and salt. Whisk to combine and break up any lumps.

In a separate bowl or large measuring cup, whisk together the whole milk, hot brewed hot chocolate (or strong coffee), vegetable oil, eggs, and vanilla extract until uniform.

Create a well in the center of the dry ingredients and pour in the wet mixture. Stir gently with a spatula or wooden spoon until just combined and no large streaks of flour remain — do not overmix.

Pour the batter into the prepared 9-inch pan and smooth the top. Bake in the preheated oven for 30–36 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs (not wet batter). Rotate the pan halfway through baking for even rise.

Allow the cake to cool in the pan on a wire rack for 15 minutes, then run a knife around the edge and invert onto the rack to cool completely. Once cool, level the top with a serrated knife if needed to create a flat surface for filling.

While the cake bakes or cools, make the gianduja. In a food processor, pulse the toasted hazelnuts until they become a fine meal and then begin to release oils and form a paste (hazelnut butter). Stop and scrape sides as needed — this takes 3–7 minutes depending on your processor.

Add the powdered sugar, chopped bittersweet chocolate, neutral oil, and salt to the food processor with the hazelnut paste. Process until glossy, smooth and spreadable, scraping down sides as necessary. If too thick, add an extra 1 teaspoon of oil at a time until spreadable but still firm.

Transfer the gianduja to a bowl and allow to cool to near room temperature if still warm from chocolate; it should be spreadable but not runny.

If the cake is one layer, slice horizontally into two even layers with a serrated knife or cake leveler. If you prefer a single thicker layer, omit slicing and instead pipe or dollop gianduja onto the top.

Place the bottom cake layer on a serving plate. Spread two-thirds of the gianduja evenly over the bottom layer, leaving a small border at the edge. If you kept a single layer, spread lightly across the top.

Top with the second cake layer and press gently to adhere. Reserve remaining gianduja for decoration or to pipe a ring on top before glazing.

Make the glaze: heat the heavy cream in a small saucepan over medium heat until it just begins to simmer and small bubbles form at the edge; do not boil. Remove from heat and pour over the chopped bittersweet chocolate in a heatproof bowl. Let sit for 1 minute, then stir until smooth.

Stir in the butter and corn syrup (or honey) until glossy. If glaze is too thick to pour, warm it gently over a double boiler or microwave in short bursts (5–10 seconds) until pourable, stirring between bursts.

Place the assembled cake on a wire rack over a baking sheet to catch drips. Pour the glaze over the center of the cake and use an offset spatula to nudge it toward the edges so it drips down the sides evenly. Work quickly before glaze sets.

While glaze is still tacky, spoon or pipe the remaining gianduja onto the top in decorative dollops or a small ring, then sprinkle toasted hazelnut nibs or chopped hazelnuts around the top edge. Dust lightly with cocoa powder if desired.

Allow the glaze to set at room temperature for 30–60 minutes, or chill briefly (10–15 minutes) to speed setting, then transfer to serving plate. Bring to room temperature before slicing for best texture.