Combine all cookie crust ingredients in a large bowl and mix until evenly combined.
Line a 10x15” baking sheet with parchment paper. Pour in cookie crust ingredients and press with spoon or fingers into an even layer (TIP: dip back of spoon or fingers in flour to prevent sticking).
Bake for 15-18 minutes until slightly browning on the edges. Remove from oven and let cool completely.
Combine frosting ingredients in the bowl of a mixer and whip until light and fluffy. Spread on cooled cookie crust.
Add blueberries for the stars of the flag and sliced strawberries for the stripes.
Notes
NOTE: You can prep the elements of this fruit pizza in advance but wait to assemble until right before you eat. You can bake the crust and cover it, whip up the frosting and store in an airtight container in the fridge, and wash and dry the fruit. Frost and layer with fruit right before serving.