Preheat oven to 325°.
Mix flour, butter, and powdered sugar together in a food processor until a dough ball forms.
Roll on a pastry mat covered with a sheet of waxed paper. Lightly flour the rolling pin and roll into a 14" diameter circle. Roll the dough around the wax paper and gently press into a 14" pizza pan.
Bake at 325° for 15 minutes or until lightly browned. Let cool completely.
Combine cream cheese, sugar, and vanilla and blend with an electric mixer until light and fluffy. Spread on cooled crust.
Mix mashed strawberries, sugar, and cornstarch in a saucepan over medium low heat. Cook until slightly thickened, about 15 minutes.
Cool completely and spread on top of frosting.
Top with sliced strawberries. Refrigerate until ready to serve.