Moist chocolate sheet cake smothered in vanilla buttercream and decorated with berries. This festive flag cake is as cute as it is delicious. The cake itself is already vegan; the buttercream can easily be made vegan too!
Chocolate wacky cake base:
2 cups all-purpose flour
1 1/2cupsgranulated sugar
1/2 cup cocoa powder
1 1/2 teaspoons baking soda
1teaspoonfine-grain sea salt or table salt
2 teaspoons pure vanilla extract
2 tablespoons white vinegar or cider vinegar
1/2cupvegetable oil or melted coconut oil
2sticks unsalted butter, room temperature1 cup) (or Earth Balance buttery sticks for vegan version
1teaspoonpure vanilla extract
6ouncesabout 1 cup or 1/2 pint fresh blueberries, washed and dried
32ouncesabout 6 cups, 2 pounds, or 2 1/2 pints fresh strawberries, washed, hulled, halved, and patted dry
Preheat oven to 350 degrees Fahrenheit. Grease a 13" x 18" rimmed baking sheet - spray with your favorite non-stick spray or wipe down with a bit of oil.
In a large bowl, sift together the flour, sugar, cocoa powder, baking soda, and salt. Stir with a whisk or a wooden spoon to combine.
Using the back of a wooden spoon, make three indents in the flour mixture. Into one indent, pour the vanilla. Into the second, pour the vinegar. Into the third, add the oil. Pour the water over the top. Stir well until combined.
Spread the batter in the baking sheet and, using an offset spatula, spread the batter to the edges of the pan, making it as level as possible. Bake for 14-17 minutes; until the sides have pulled away from the edge a bit and a toothpick inserted into the center comes out clean. Pull the cake out of the oven and set on a wire rack to cool completely.
While the cake cools, make the buttercream frosting. Using a stand mixer or hand mixer, whip the butter until smooth. Add a cup of powdered sugar and mix in at low speed. Add remaining powdered sugar, a cup at a time, and mix until smooth. Add the vanilla and the milk. Mix until smooth and an easily spreadable consistency. If too thick, add more milk - just a teaspoon at a time, as it thins out easily. If too thin, add more powdered sugar.
Once the cake is completely cool, frost it with the buttercream - simply smooth it all over the top in a thin, even layer.
Now, it's time to decorate! Visually divide the cake into thirds and, in the top third, fill in with rows of blueberries. Add rows of halved strawberries next; the amount of stripes depends on the size of your strawberries, so just eyeball it, and if you need to adjust the berries, you can use the tip of the offset spatula or the tip of a spoon to create stripes in between the rows of berries.
Serve as soon as possible; it can be made ahead of time, but the strawberries will probably start to leak after awhile, so keep that in mind.
Make ahead: You can bake the sheet cake ahead of time (just cover with plastic wrap and keep at room temp until you're ready to frost). I recommend frosting and adding the berries as close to serving time as possible. The sugar in the frosting brings out some of the juices in the berries, so if it sits for awhile, the strawberries start leaking a bit.
The cake recipe is already vegan; to make the frosting vegan, use Earth Balance for the butter and almond or soy milk instead of dairy milk.