Preheat the oven to 350. Add the softened butter, brown sugar, sugar, and cookie butter to a bowl. Mix for 2-3 minutes until smooth and lighter.
Add egg and vanilla and mix until fully combined.
Add flour, baking soda, and salt. Mix until the dough just comes together. Add the white chocolate chips and biscoff cookie pieces. Pulse a few times until the mix-ins are just distributed.
Use a medium cookie scoop to scoop out the dough. Place up to 6 dough balls on a parchment paper lined baking sheet.
Transfer the cookies to the oven and bake for 10-12 minutes, until cookies are just golden brown on top.
Leave the cookies on the baking sheet for 5 minutes, then transfer to a cooling rack to cool completely. Enjoy!