01 - Preheat the oven to 350°F. Line a baking sheet with parchment paper or use a 9x13-inch baking pan.
02 - In a large bowl, beat the softened butter and granulated sugar with an electric mixer until light and fluffy. Mix in the egg and vanilla extract until well incorporated.
03 - In a separate bowl, whisk together the all-purpose flour, baking powder, and salt. Gradually blend the dry mixture into the butter mixture until a cohesive dough forms.
04 - Press the dough evenly into the prepared pan to achieve a uniform crust approximately 1/4 inch thick. Bake for 13 to 15 minutes, or until edges are set and lightly golden. Remove from oven and allow to cool completely.
05 - In a clean bowl, beat the softened cream cheese and butter together until smooth and creamy. Incorporate the powdered sugar and vanilla extract, mixing until no lumps remain.
06 - Once cooled, evenly spread the cream cheese frosting over the surface of the cookie crust using a spatula.
07 - Arrange blueberries in the top left corner to mimic the flag’s stars. Alternate rows of strawberries and raspberries to create red stripes, allowing white frosting to show for contrast.
08 - Chill in the refrigerator for at least 30 minutes before slicing and serving.