-
1
Preheat your oven to 350 F and spray a 9-inch pie dish with a non-stick spray. Set aside.
-
2
In a medium bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt. Set aside.
-
3
In the bowl of your stand mixer, with paddle attachment fixed (or with a handheld electric mixer), cream together the butter and sugars until smooth, creamy and fully combined, about 1 minute. Add the egg, milk and vanilla extract. Beat again, until incorporated.
-
4
With the mixer set on low speed, gradually add the dry ingredients to the wet. Mix until fully incorporated, about 1 minute. Fold in the white chocolate chips until evenly dispersed.
-
5
Pour the cookie dough into the prepared pan. Smooth it over so that it is even. Bake at 350 F for 25 minutes or until the top is lightly browned. The center should still be soft to the touch.
-
6
Remove from the oven and transfer to a wire rack to cool completely before you frost the cookie.
-
7
Prepare your frosting by creaming together the butter and confectioners' sugar in the bowl of your stand mixer until fully combined, about 1-2 minutes. Add the milk, vanilla extract and salt and mix again for 1-2 minutes.
-
8
Frost the cookie cake once cool, sprinkle with sprinkles, cut into slices and serve! The sugar cookie cake will store at room temperature in an airtight container for 3-4 days. Enjoy!
-
9
Inspired and slightly adapted from Sally's Baking Addiction.