Preheat oven to 350° F. Line an 8x8 baking dish with parchment paper and set aside.

Melt butter in a medium saucepan on medium heat, stirring until fully melted and browned (6-10 minutes).

Once the butter is browned, pour it into a heat-proof bowl and let it cool for about 5-10 minutes.

In a medium bowl, add cooled butter and brown sugar, mixing until combined.

Add the egg and yolk, mixing until incorporated. Add the Biscoff spread and mix.

Add the salt and flour, mixing until fully incorporated. Lastly, add the chopped chocolate and mix until combined.

Pour the batter into the prepared baking pan, top with chopped chocolate and Biscoff cookies, and bake for 20-25 minutes.

Remove from oven and allow to cool completely before slicing.