Line a 13x9" (33x23cm) pan with parchment paper (if not using a silicone pan).
Mix or blend all cake ingredients until smooth.
Pour batter into pan.
Bake for about 20 minutes, until the cake is firm and a toothpick comes out clean.
Let the cake cool to room temperature.
Once cool, top the cake with cashew whipped cream.
Make the flag design by first placing blueberries, then following with strawberry stripes.
Slice, and enjoy!
Store in the refrigerator.
Notes
A note about substitutions: because each type of protein powder has a distinct flavor and texture when baked, I would not try substituting different types of protein powders in this recipe (other than a pea blend like Warrior Blend).