Blackberry Cake with Blackberry Buttercream Frosting

Blackberry Cake with Blackberry Buttercream

Adapted from Confections of a Foodie Bride and Cook’s Illustrated

For the puree:
18 oz. blackberries (3 six-ounce packages)

For the cake:
1/3 cup milk, room temperature
6 large egg whites, room temperature
2 tsp. lemon juice
2/3 – 3/4 cup blackberry puree
2-1/4 cups cake flour, sifted
1-3/4 cup sugar
4 tsp. baking powder
1 tsp. salt
12 Tbsp. (1.5 sticks) unsalted butter, softened

For the frosting:*
24 Tbsp. (3 sticks) unsalted butter
1 tsp. vanilla extract
1/4 tsp. almond extract
6-8 cups confectioners sugar, sifted
1.5 Tbsp. meringue powder (optional)
1/3 cup blackberry puree
milk (if necessary)

To make the puree, process the blackberries in a food processor or blender until smooth. Set a fine mesh sieve over a bowl and push the puree through, leaving the seeds behind. You should get 1-1.25 cups of puree.

To  make the cake, preheat the oven to 350. Line two 8″ or 9″ round pans with parchment and mist with cooking spray.

In a medium bowl, combine the milk, egg whites, lemon juice, and puree. Mix with a fork until just blended. In the bowl of a stand mixer (or a large mixing bowl), add the sifted flour, sugar, and baking powder, mixing to combine. With the mixer at low speed, start adding the butter. Mix until combined and resembling moist crumbs.

Add the liquids to the stand mixer and beat at medium speed for about a minute, until evenly combined. Scrape down the sides of the bowl and beat for an additional 30-60 seconds. Divide the batter between the two prepared baking pans. Bake for about 25 minutes, or until a toothpick inserted comes out clean. Cool the cake in pans for 10 minutes and then invert onto a wire rack to cool completely.

To make the frosting, cream the butter and extracts until smoothed. Add the meringue powder (if using) and then slowly add the confectioners sugar, one cup at a time (start with 5-6 cups; you can add more later). Beat in the blackberry puree. If the frosting is too runny or not sweet enough, beat in additional sugar. If you go to far with the sugar, add a little milk to thin it out. Frost the cooled cakes.

*Note: You will have a little leftover frosting. You can make a higher cake by slicing each cake into two before stacking, use it for decoration/piping, or simply reduce the recipe. Last time I made a layer cake with 2 sticks of butter it was just not quiiiiiiiiiite enough but if you want thin layers of frosting, follow the recipe in Shawnda’s post.