Make the Crust: In a large bowl, mix the softened butter, granulated sugar, egg, and vanilla extract until well combined and creamy. (An electric mixer works best, but you can mix with a spoon if butter is very soft or slightly melted). Add the flour, baking powder, and salt. Mix until just combined to form a soft dough. Chill the dough in the refrigerator for at least 30 minutes.

Bake the Crust: Preheat your oven to 350°F (175°C). Line a large round baking stone or a 12-inch pizza pan with parchment paper. Roll the chilled dough out onto the prepared surface into a 1/4 to 1/2-inch thick layer, leaving a small border around the edge. Bake for 20-25 minutes, or until the edges are lightly golden. The center should be slightly soft. Let the cookie crust cool completely on a wire rack.

Make the Cream Cheese Frosting: While the crust cools, using an electric mixer, combine the softened cream cheese, softened butter, powdered sugar, and vanilla extract until smooth, light, and creamy. Spread this frosting evenly over the cooled cookie crust. Chill the frosted crust in the refrigerator for at least 30 minutes to allow the frosting to firm up.

Assemble the Fruit Pizza: Arrange the sliced strawberries, kiwis, mango, blueberries, and halved grapes decoratively over the chilled cream cheese frosting. Get creative with your design! Serve immediately or keep chilled until ready to serve.