In a mixing bowl, combine the softened butter and granulated sugar. Use a spatula or mixer to cream together until the mixture is light and fluffy, with a pale color and smooth texture.
Add the all-purpose flour and vanilla extract to the creamed mixture. Mix until the dough comes together and is uniform, stopping when no dry flour remains.
Transfer the dough onto a lightly floured surface, then roll it out with a rolling pin to about 1/4-inch thickness. Use a round cookie cutter or the rim of a glass to cut out a large circular crust, then place it on a baking sheet lined with parchment paper.
Bake the crust in a preheated oven at 350°F (175°C) for about 10 minutes, or until it turns golden around the edges. Remove from oven and allow to cool completely on a wire rack.
In a separate bowl, beat the softened cream cheese, powdered sugar, and lemon juice until smooth and creamy. Spread this layer evenly over the cooled cookie crust using a spatula.
Decorate the top with strawberries, blueberries, and kiwi slices to resemble the flag—red strawberries for stripes, blueberries for the canton, and kiwi for additional accents. Arrange the fruits neatly to create a colorful, flag-like pattern.
