Berry Layer Cake with Vanilla Buttercream
When the occasion calls for an extra-special dessert, whip up this towering layer cake, which offers a pop of juicy blackberries in every bite. A thin coating of rich buttercream on the top and sides shows off the beautiful cake underneath. When folding the beaten egg whites into the batter, be gentle so you don’t deflate the peaks. The whites help to lighten the cake and ensure a high rise.
Ingredients
For the cake:
- 12 Tbs. (1 1/2 sticks) (6 oz./185 g) unsalted butter, at room temperature, plus more for greasing
- 2 3/4 cups (14 oz./440 g) all-purpose flour, plus more for dusting
- 2 1/2 tsp. baking powder
- 3/4 tsp. baking soda
- 3/4 tsp. kosher salt
- 3 egg whites plus 1 whole egg
- 2 cups (1 lb./500 g) granulated sugar
- 1 Tbs. vanilla extract
- 1 1/2 cups (12 fl. oz./375 ml) buttermilk
- 18 oz. (560 g) blackberries
For the buttercream:
- 32 Tbs. (4 sticks) (1 lb./500 g) unsalted butter, at room temperature
- 3 1/2 cups (14 oz./440 g) confectioners’ sugar
- 1 Tbs. vanilla bean paste
- 1/4 tsp. kosher salt
- 1 tsp. heavy cream or milk, if needed
- 3 Tbs. blackberry preserves
- 1 cup (4 oz./125 g) blackberries
- 1 cup (4 oz./125 g) blueberries
Directions
To make the cake, preheat an oven to 350°F (180°C). Grease three 8-inch (20-cm) round cake pans, line the bottom of each pan with parchment paper and butter the parchment. Dust with flour, then tap out any excess.
In a bowl, sift together the flour, baking powder, baking soda and salt. Set aside.
In the bowl of a stand mixer fitted with the whisk attachment, beat together the egg whites and 1 cup (8 oz./250 g) of the granulated sugar on medium-high speed until soft peaks form, about 4 minutes. Transfer the egg whites to another bowl. Set aside.
In the clean bowl of the stand mixer fitted with the flat beater, beat together the butter and the remaining 1 cup (8 oz./250 g) granulated sugar on medium speed until light and fluffy, about 2 minutes. Add the whole egg and vanilla and beat until combined, about 1 minute. Stop the mixer and scrape down the sides of the bowl. With the mixer on low speed, add the flour mixture in 3 additions, alternating with the buttermilk and beginning and ending with the flour, and beat until combined. Stop the mixer and scrape down the sides of the bowl. Increase the speed to high and beat for 20 seconds. Remove the bowl from the mixer.
Using a rubber spatula, gently fold the egg whites into the butter mixture until completely incorporated, taking care not to deflate the peaks. Gently fold in the blackberries.
Divide the batter evenly among the prepared pans and smooth the tops. Bake until a toothpick inserted into the center of the cakes comes out clean, 40 to 45 minutes. Transfer the pans to wire racks and let cool for 10 minutes, then invert the cakes onto the racks and let cool completely.
To make the buttercream, in the clean bowl of the stand mixer fitted with the clean flat beater, beat the butter on medium speed until smooth, about 3 minutes. Add the confectioners’ sugar in 3 additions, beating well after each addition. Add the vanilla and salt, increase the speed to medium-high and beat until combined, about 1 minute, stopping the mixer to scrape down the sides of the bowl as needed. If the frosting seems dry, add the cream and beat until combined.
To assemble the cake, place 1 cake layer on a cake stand or serving plate. Spread about one-fourth of the buttercream over the top of the cake, then spread 1 Tbs. of the blackberry preserves over the buttercream. Place another cake layer on top of the first and spread another one-fourth of the buttercream and 1 Tbs. preserves over the cake. Top with the third cake layer and spread a very thin layer of buttercream over the top and sides of the cake. Follow with a few artful strokes of blackberry preserves on the top and sides. Decorate as desired with blackberries and blueberries. Cut the cake into slices and serve. Serves 12 to 16.
Williams Sonoma Test Kitchen
