Start by lining a 9x9-inch baking pan with parchment paper, allowing some overhang on the sides for easy removal later.
In a microwave-safe bowl, combine the 1 cup of semi-sweet chocolate chips and melt them in the microwave in 30-second intervals, stirring in between until the chocolate is smooth and fully melted.
Once melted, stir in the ½ cup of Biscoff Spread into the chocolate until fully combined.
Fold in the 3 cups of mini-marshmallows gently into the chocolate-Biscoff mixture.
Next, crumble the 1 cup of Biscoff cookies and fold them into the mixture.
Pour the mixture into your prepared baking pan, spreading it evenly with a spatula.
Sprinkle the ½ cup of semi-sweet chocolate chips evenly over the top.
Place the baking pan in the refrigerator for about 2 hours or until the bars are set and firm.
Once set, lift the bars out of the pan using the parchment overhang. Cut them into squares and serve.
