One of the things I love most about summer is that it comes with no shortage of opportunities to get together with family and friends al fresco. Another thing I love is being able to bring something delicious to share! Packed with strawberries, raspberries and blueberries, my Triple Berry Flag Cake embodies the very essence of summer. Beautiful berries are everywhere and this cake allows you to use all of the berries from your garden or that you picked up at the farmer’s market or farm stand. While it looks complicated, this dessert is simply a classic “sheet cake” made from my Lemon Pound Cake and bursting with fresh strawberries and blueberries baked inside, a crème fraiche-infused buttercream and finished with a festive (and easy!) step-by-step iconic decoration of fresh blueberries and raspberries on the outside that will impress your guests all season long!
Triple Berry Flag Cake
Ingredients (serves 20-25 people)
Flour – 3 cups, all-purpose, plus more for preparing the pan
Sea Salt – 1 teaspoon
Baking Powder – ½ teaspoon
Baking Soda – ½ teaspoon
Butter – 16 tablespoons (2 sticks), unsalted, at room temperature, plus more for preparing the pan
Sugar – 2 cups, granulated
Vanilla – 2 teaspoons, pure extract
Lemon – 2 large lemons, zested and juiced
Honey – ¼ cup, clover honey preferred
Eggs – 4 extra-large, at room temperature
Buttermilk – 1 cup, at room temperature
Blueberries – (1) half-pint
Strawberries – 1 pound, hulled, ¼-inch diced
Cream Cheese – 1 pound, at room temperature
Crème Fraiche – 8 ounces, at room temperature
Butter – 1 pound, unsalted, at room temperature
Sea Salt – ¾ teaspoon
Vanilla – ½ teaspoon, pure extract
Confectioners Sugar – 1 pound, sifted
Blueberries – (2) half-pints
Raspberries – (3) half-pints
Preheat the oven to 350 degrees F. Butter a half sheet pan (18” x 13” x 1”). Line the bottom of the pan with a piece of parchment paper. Butter the top of the parchment paper. Lightly dust the entire pan with flour. Set aside.
In large bowl sift together the flour, salt, baking powder, and baking soda. Set aside.
In the bowl of an electric mixer fitted with a paddle attachment, cream together the butter and sugar on medium speed until light and fluffy.
Turn the mixer to low speed and add the vanilla, lemon juice, lemon zest, honey, and the eggs one at a time, allowing each to fully incorporate.
Next, add the flour mixture and buttermilk alternately, beginning and ending with the flour mixture.
Scrape down the sides and bottom of the mixing bowl. Gently fold in the berries.
Transfer the batter into the prepared pan. Tap the pan on a flat surface to release as many air bubbles as possible.
Bake for 35 to 45 minutes, or until a toothpick inserted in the middle of the cake comes out clean.
Remove the pan from the oven, allow the cake to cool in the pan for 10 minutes. Then, turn the cake out onto a wire rack to cool completely.
Buttercream & Assembly
In the bowl of a stand mixer fitted with a paddle attachment, add the cream cheese, crème fraiche, butter, salt and vanilla. Turn the mixer to low speed and gradually add the confectioner’s sugar. Raise the speed to medium-low and mix until smooth.
Place the completely cooled cake onto a large serving platter or board.
Spread half of the icing on the top of the cooled sheet cake. Using a toothpick, outline the flag on the top of the cake. Fill the upper left third corner with blueberries.
Put the remaining buttercream in a pastry bag fitted with a large star tip and pipe two rows of white stripes. Place 2 rows of raspberries below the piped row to create a red stripe. Alternate rows of buttercream and raspberries until the flag is completed. Pipe small stars on top of the blueberries.
Tip: If you are brining this cake to a party, after the cake has cooled completely on the wire rack, simply place it back into the sheet pan, decorate it and then transport it and serve directly from the sheet pan. This will ensure this show-stoping cake can be your signature summer pot-luck dessert all season long!
Trick: The sheet cake can be made up to two days in advance. Once the cake has cooled completely, wrap it tightly in plastic wrap and store it in the refrigerator.
Summer Tip: On a hot day you may have to periodically place the finished buttercream into the refrigerator for 5-10 minutes so it stays firm and easy to use while you decorate the cake.