Whisk together flour, cornstarch, baking powder, and salt in a medium bowl. Set aside.
Beat softened butter and granulated sugar on medium-high speed for 3 minutes until pale and fluffy.
Add egg and vanilla extract and beat until fully incorporated.
Add flour mixture and beat on low until just combined. Do not overmix.
Cover dough with plastic wrap and refrigerate for at least 20 minutes.
Preheat oven to 350 degrees F. Grease a 12-inch pizza pan with nonstick spray.
Press chilled dough evenly into a 9 to 10-inch circle on the prepared pan, about 1/3 inch thick.
Bake for 17 to 19 minutes until edges are very lightly browned and center looks just set.
Cool completely on a wire rack, at least 45 minutes to 1 hour.
Beat cream cheese and butter together until completely smooth, about 2 minutes.
Add confectioners' sugar and vanilla extract, beat until creamy and smooth.
Spread frosting evenly over the cooled crust.
Arrange sliced fresh fruit over the frosting and serve. Refrigerate leftovers up to 3 days.