In a bowl, whisk together flour, cornstarch, baking powder, and salt.
In another bowl, cream together butter and 3/4 cup Splenda Magic Baker Sweetener. Mixture will break apart into a course sand-like texture, and then as you keep beating, it will come together again. Add extracts and egg and continue to beat.
Add flour mixture to wet ingredients in two batches, mixing on low until combined.
Using a cookie scoop, place each cookie dough ball onto a baking sheet lined with parchment paper, and spacing the cookies two inches apart. Bake for 9-10 minutes. Cookies should still look just little doughy in the middle. Remove from oven. Sprinkle a little more sweetener onto each cookie. Let cool completely.
Note
Cookie dough can be made two days ahead and stored in the refrigerator.
Press sugar-free sprinkles into the tops of the cookies before baking for a fun twist.