Preheat oven to 350°F. Prepare pizza pan with vegetable pan spray.

In large bowl, stir together flour, baking powder and salt.

In second large bowl, beat butter and sugar with electric mixer on medium speed until light and fluffy. Add egg, milk and vanilla; mix until well combined. Add flour mixture and mix until just combined. Press into prepared pan. Prick dough with fork.

Bake 15 to 20 minutes or until golden brown. Cool completely in pan on cooling grid.

Spread thawed whipped topping over cookie crust and top with berries. Garnish with mint leaves, if using. Serve immediately.