Preheat oven to 350 degrees F. and line a 9 x 13 inch baking dish with parchment paper.
Place butter and sugars into a large mixing bowl or stand mixer. Beat until well combined, a good minute or two. Stir in eggs and vanilla, mixing until creamy and smooth. Add flour, pudding mix, salt and baking soda. Slowly mix until dough forms them stir in white chocolate chips to combine. Transfer half of the cookie dough to the baking dish, pressing until even on bottom. Spread evenly with Biscoff Cookie Butter. Use a cookie scoop to scoop remaining dough on top of Biscoff layer. Use fingers to carefully press and spread. Won't be perfect or cover the entire area. Bake for 30-35 minutes, or until baked through in the center. Remove and let cool for 1 hour before cutting into squares.