Preheat the oven to 350 degrees F (175 degrees C). To make the cookie crust: Combine flour, cream of tartar, baking soda, and salt in a medium bowl and set aside. Cream together the butter and 3/4 cup sugar until smooth in a large bowl. Add in the egg and beat well. Stir dry ingredients into the creamed mixture until just blended. Press dough into an ungreased pizza pan. Bake in the preheated oven until lightly browned, eight to 10 minutes. Cool. To make the filling: Beat cream cheese with the remaining 1/2 cup sugar and vanilla in a large bowl until light and fluffy. Spread evenly over the top of the cooled crust. Arrange blueberries, strawberries, grapes and kiwi on top of the filling, and chill. Yields one pizza.