Equipment
Ingredients
Cake Batter
- 250 g all-purpose flour, sifted
- 10 g baking powder
- 3 g salt
- 225 g unsalted butter, room temperature
- 200 g granulated sugar
- 100 g brown sugar, light or dark, packed
- 4 eggs, room temperature
- 120 ml whole milk, room temperature
- 15 g instant coffee, espresso powder preferred
- 30 ml water, boiling
- 100 g walnuts, toasted and chopped
Espresso Buttercream
- 340 g unsalted butter, room temperature
- 400 g powdered sugar, sifted
- 10 g instant coffee
- 15 ml vanilla extract
- 15 ml heavy cream, room temperature
- 2 g salt
Nutrition (per serving)
Method
Preheat the oven to 175°C/350°F. Grease two 8-inch round cake pans and line the bottoms with parchment paper.
In a mixing bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream the room temperature unsalted butter, granulated sugar, and brown sugar on medium speed until pale, light, and fluffy.
Add the eggs one at a time to the butter mixture, mixing well on low speed after each addition and scraping down the sides of the bowl as needed.
Dissolve the instant coffee in the boiling water. In a small jug, combine the dissolved coffee mixture with the room temperature whole milk.
Add the dry ingredients to the butter mixture in three additions, alternating with the coffee-milk mixture, beginning and ending with the dry ingredients. Fold gently until just combined.
Gently fold the toasted, chopped walnuts into the batter using a rubber spatula.
Divide the batter evenly between the prepared cake pans. Bake for 30 to 35 minutes at 175°C/350°F, or until a skewer inserted into the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes before turning them out onto a wire rack to cool completely.
For the espresso buttercream, place the softened unsalted butter in a clean stand mixer bowl and beat on medium speed until creamy. Gradually add the sifted powdered sugar on low speed.
Dissolve the remaining instant coffee in the vanilla extract and heavy cream. Pour this liquid into the buttercream along with the salt. Whip on medium-high speed until the frosting is light, airy, and thoroughly emulsified.
Place one completely cooled cake layer on a serving plate. Spread an even layer of buttercream over the top using an offset spatula. Place the second cake layer on top and use the remaining buttercream to frost the top and sides of the cake.
Chef's Notes
- Toasting the walnuts before folding them into the batter is crucial; it draws out their essential oils and ensures they stay crisp against the moist crumb of the cake.
- The quality of your instant coffee directly impacts the final flavor. Choose a premium espresso powder or high-quality instant coffee that dissolves fully without granular residue.
- Ensure your butter, eggs, and milk are truly at room temperature. The emulsion of the butter and sugars relies on equal temperatures to trap air, giving the cake its structural lift.
- This recipe intentionally uses a high ratio of coffee to temper the classic American buttercream. The bitterness cuts through the powdered sugar, pulling it back from cloying sweetness to a deep, sophisticated roasted profile.
- When frosting the cake, a brief crumb coat followed by 15 minutes in the refrigerator will lock in any loose walnut bits, making the final outer layer of frosting perfectly smooth.
Storage
Refrigerator: 5 days — Store in an airtight cake dome or container to prevent the crumb from drying out. Bring to room temperature before serving.
Freezer: 1 month — Freeze slices individually wrapped in plastic wrap and foil.
