Preheat oven to 350 degrees F. Grease 9x13" baking dish, and set aside.

In medium bowl, combine flour, baking powder, baking soda, and salt. Set aside.

In large bowl with electric mixer, beat together melted butter and brown sugar until well combined, about 2 minutes.

Add eggs and egg yolk, one at a time, mixing completely between each addition.

Add vanilla and Biscoff and mix to combine.

Slowly add flour mixture to Biscoff mixture, mixing until combined.

Fold in chocolate chips.

Pour into prepared baking dish and spread evenly.

Bake in preheated oven until edges are golden brown and top is lightly golden, about 25-30 minutes.

Cool completely, and cut into squares.

Enjoy!