Preheat oven to 350 degrees. Butter a round baking pan.
Cream the butter and sugar together until light then beat in egg.
Add flour, salt, and baking powder and stir together. Then add to butter mixture and mix until dough comes together.
Shape into a ball and gently press into a circle on a buttered round baking pan.
Using a rolling pin or your hand, press into a ⅓-½ inch circle.
Bake in center of oven for 15 minutes, until edges are just beginning to brown, but center still looks slightly underdone.
Remove from oven and let cool completely on the pan.
To make frosting using electric beaters, beat cream in bowl until stiff peaks form.
In a separate bowl, beat cream cheese and powdered sugar together until smooth. Then fold in beaten cream.
Spread over top of cooled cookie pizza.
Arrange sliced strawberries and blueberries on top of pizza.
Melt white chocolate chips and drizzle over fruit.
Serve immediately or cover and chill in the refrigerator.