Preheat the oven to 350° F (180·C). Spray a 9x13 pan with non-stick spray and set aside.
In the bowl of a stand mixer or with an electric hand mixer, cream together the butter, brown sugar, and granulated sugar until light in color and fluffy in texture. This will take about 2 minutes.
Scrape down the sides and add in the egg and vanilla. Mix until well combined.
Next, add the dry ingredients (flour, baking soda and salt). Mix until incorporated and add the white chocolate chips.
Once a soft dough has formed, you will press half of the dough into the bottom of the prepared pan.
Using a spatula or spoon, spread the Biscoff cookie butter on top of the cookie dough in the pan.
On top of the biscoff layer, crumble the remaining cookie dough and press it in slightly.
Bake at 350°F (180°C) for 15-17 minutes.
Allow the bars to cool completely before cutting and serving. Enjoy!
