01 - Line a 9x9-inch square pan with parchment paper and lightly grease the surface.
02 - In a large saucepan over low heat, melt unsalted butter. Add Biscoff spread and stir until smooth.
03 - Add mini marshmallows to the saucepan and cook, stirring constantly, until completely melted and combined with the Biscoff mixture.
04 - Remove pan from heat. Immediately fold in Rice Krispies cereal, mixing until evenly coated.
05 - Press the mixture gently and uniformly into the prepared pan using a greased spatula or wax paper.
06 - Drizzle melted Biscoff spread evenly over the surface and sprinkle with crushed Biscoff cookies if using.
07 - Allow treats to cool at room temperature for approximately 45 minutes or until fully set.
08 - Cut into 16 squares and serve as desired.