Preheat the oven to 410°F and line a cookie sheet with parchment.
Crush your biscoff cookies. You’ll want some larger chunks and some smaller for optimal texture.
In the bowl of your stand mixer (or with an electric hand mixer in a large bowl), cream unsalted butter with the brown and white sugar for 2 minutes or until smooth.
Add in the Biscoff cookie spread and continue to mix for another minute.
To the butter mixture add the vanilla extract and then the large eggs, one at a time and continue to beat.
Once the wet ingredients are thoroughly combined, scrape down the sides of the bowl and add in all purpose flour, baking soda, corn starch, and salt.
Mix together allowing some white streaks to remain.
Add in the cake flour and mix, again with a little bit of white streaks remaining.
Stir in crushed cookies and chocolate chips if you’re using.
Use a cookie scoop to scoop into 12-18 cookies (depending how large you like them) onto the prepared baking sheet. Press a few of the remaining biscoff cookie crumbs on top of each cookie.
Bake for 10-12 minutes, or until the edges are dark and middles have begun to set. Larger cookies will take slightly more time. Note: middles may look slightly underdone. They will continue to bake as they cool.
After 10 minutes, transfer to a wire cooling rack. Enjoy!