Chocolate Sheet Cake with Triple Berry Buttercream

 

We've been joking that this has been the "Summer of Caroline."  She's been to art camp, princess camp, VBS, preschool camp... and we capped off the month of June with a surprise birthday trip to the happiest place on earth.  Disney World!  We left the boys with family and took her on a solo vacation, and of course she had the time of her life.  Meeting princesses, having breakfast with Mickey Mouse, hanging out with one of our favorite families ever, and basically having her dreams come true - yeah, it was pretty awesome.  We came home just in time to celebrate her FIFTH birthday the following day, then celebrated with a birthday party on Saturday.  This weekend we're attending my cousin's wedding, where she'll be a flower girl, and in the following weeks we'll be taking a family vacation to the beach, she'll go to music camp, and then get ready to start kindergarten (sob).  Summer of Caroline indeed.

When we woke up on her birthday, I asked her what she wanted to do that day.  Without missing a beat, she said that she wanted to help me bake a cake.  I was totally down with that.  She requested chocolate with strawberry frosting, and I was more than happy to oblige..  mostly.  We didn't have enough strawberries for the frosting - we had two, actually.  So instead, I used a mixture of raspberries, blueberries, and blackberries to create an out of this world delicious buttercream.

Since I had a five year old helping me, I decided that we'd go the easy and "rustic" route, baking up a sheet cake and then just slathering the frosting on.  There are times when I love beautiful and meticulously frosted cakes, but sometimes it's fun to let loose a little and just slap it on.  I topped the whole thing with a huge pile of fresh berries, and let me tell you - the berries MADE it.  The combination of the rich chocolate cake, sweet and decadent buttercream, and bright and fresh berries was just wonderful.  I made sure to get at least one berry in every bite. :)

I know that the frosting is purple, but this would still be a pretty fabulous dessert for the Fourth of July -  not every dessert has to be red, white, and blue, after all.

 

Chocolate Sheet Cake with Triple Berry Buttercream
cake adapted from Hershey's
buttercream adapted from Martha Stewart's Strawberry Buttercream

• 2 cups sugar
• 1 3/4 cups all-purpose flour
• 3/4 cup unsweetened cocoa powder
• 1 1/2 tsp baking soda
• 1 1/2 tsp baking powder
• 1 tsp salt
• 2 eggs
• 1 cup buttermilk
• 1/2 cup vegetable oil
• 2 tsp vanilla extract
• 1 cup hot coffee

Preheat the oven to 350 degrees.  Butter and flour a 9x13 inch baking dish, and/or line with parchment paper.

In the bowl of a stand mixer fitted with the paddle attachment, whisk together the sugar, flour, baking soda, baking powder, cocoa powder, and salt.  Stir the ingredients together over low speed.  Add the eggs, buttermilk, vegetable oil, and vanilla.  Mix at medium speed until well-combined, about 2-3 minutes.  Carefully add the coffee and beat on the lowest setting to combine.  Remove bowl from the mixer and stir with a rubber spatula until well-combined.

Pour the batter into the prepared pan, and bake 35-40 minutes, or until a toothpick inserted into the center comes out clean.  Allow to cool 15 minutes in the pan, run a knife around the edge, then carefully invert onto a cooling rack to cool completely before frosting.

Triple Berry Buttercream

• 1 cup mixed berries
• 2 egg whites
• 3/4 cups sugar
• pinch of salt
• 3/4cup (1.5 sticks) unsalted butter, cut into tablespoons, at room temperature

Puree the berries in a food processor. Strain through a fine-mesh sieve to remove as many seeds as possible, and set the puree aside.

Combine the egg whites, sugar, and salt in the bowl of a stand mixer set over a small pan of simmering water.  Whisk constantly by hand until the sugar has dissolved (the mixture should feel completely smooth when rubbed between your fingertips).

Attach the bowl to the stand mixer and fit with the whisk attachment.  Starting on low speed and gradually increasing to medium-high speed, mix until stiff (but not dry) peaks form.  Continue mixing until until the mixture is light, fluffy, glossy, and completely cool (test by touching the bottom of the mixing bowl), about 10 minutes.

With the mixer on medium-low speed, add the butter 2 tablespoons at a time, mixing well between each addition.  Scrape down the sides of the bowl, increase the speed to medium, and mix until the buttercream comes together (it can take up to several minutes, but it will come together eventually).  Switch to the paddle attachement and beat at medium-low speed to remove air bubbles, about 2 minutes.  Gradually add the strawberry puree a few tablespoons at a time, and mix to combine.

Frost the cake as desired, and top with additional berries before serving.