Start by printing out the American flag outline for easy piping later. Set aside.
Wash and dry all your fresh berries. Then, remove the tops of the strawberries and slice them into 1/4-inch strips. Set aside.
1 cup fresh strawberries, 1/2 cup fresh blueberries
In the bowl of a stand mixer, combine the softened butter, salt, vanilla, and about half of the powdered sugar. Mix on low until combined, then bump up the speed to medium and mix until fluffy, scraping the sides as needed.
1 cup unsalted butter, 1 tsp salt, 1 tsp vanilla extract, 3 cups powdered sugar
Add the remaining powdered sugar and mix on low until combined. If the frosting appears dry, add a dash of water or milk.
3 cups powdered sugar
Mix until well combined and fluffy.
Transfer the frosting to a piping bag fitted with a large star tip. On wooden tray with a flat surface, place your printed flag outline under a piece of parchment paper.
Pipe straight rows of frosting on the parchment for the red and white stripes of the flag, leaving the blue corner empty for now.
Start placing the strawberries in horizontal lines to create the red stripes, leaving the white stripes empty. Alternate 13 rows of red and white, beginning and ending with red. Cut strawberries as needed to fit nicely in the rows.
1 cup fresh strawberries
Pipe the remaining corner of the flag with frosting and cover this area with a single layer of blueberries (here's a challenge for you - can you do exactly 50?).
1/2 cup fresh blueberries
Refrigerate your buttercream board for an hour to firm up a little.
Before serving, surround your flag buttercream with an assortment of dippers such as Oreos, pretzels, wafer cookies, crackers, chocolate candies, and more. Place your board at the center of your dessert table and watch it wow the crowd!