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.

Bump up the speed to medium and mix until fluffy - scraping the sides as needed.

Add in the remaining powdered sugar and mix on low until combined.

If the frosting appears dry and clumpy, add in a dash of water (or milk). Mix until combined.

Transfer the frosting to a piping bag fitted with a large star tip.

Print out and place the flag PDF (included) under a piece of parchment paper. You could free-hand if you want, but we like to keep the lines straight to know which rows get the strawberries, etc.

Pipe straight rows of frosting on the parchment for the red and white stripes of the flag (leaving the blue corner empty for now).

Starting at the top - begin placing the strawberries in a line horizontally, leaving the white stripes visible and empty of any decoration. The stripes should begin and end with red, alternating 13 rows of red and white. Cut the strawberries, if needed to fit nicely in the rows.

Pipe the remaining corner of the flag. This entire area gets covered in a single layer of blueberries. Try to size them up to fit the area nicely.

Refrigerate until ready to serve.