Preheat your mixer on medium speed. Cream together the large egg, creamy cookie butter, light brown sugar, and vanilla extract for about 4-5 minutes, until light and fluffy.

In a separate bowl, whisk together the all-purpose flour, cornstarch, cinnamon, baking soda, and a pinch of salt. Gradually add this to the creamed mixture, mixing just until combined.

Using a cookie scoop, portion out mounds of dough on a baking sheet lined with parchment paper. Flatten each mound slightly, cover with plastic wrap, and refrigerate for at least 3 hours.

Preheat your oven to 350°F (175°C) and prepare two baking sheets by lining them with parchment paper.

Space the chilled mounds on the sheets, leaving room for spreading. Bake for 8-9 minutes, until edges are set and tops appear glossy.

Allow cookies to cool on baking sheets for about 5 minutes before transferring to a wire rack to cool completely.