01 - Line a 9x9-inch square pan with parchment paper and lightly grease the surface.
02 - In a large saucepan over low heat, gently melt the butter. Add 1 cup of Biscoff spread and stir continuously until smooth.
03 - Add mini marshmallows to the saucepan and cook, stirring constantly, until melted and fully incorporated into the mixture.
04 - Remove from heat and fold in the Rice Krispies cereal until evenly coated.
05 - Transfer the mixture to the prepared pan and gently press it into an even layer using a greased spatula or wax paper.
06 - Drizzle melted Biscoff spread over the top and sprinkle with crushed Biscoff cookies if desired.
07 - Allow to cool at room temperature for approximately 45 minutes or until fully set.
08 - Cut into 16 squares and serve at room temperature.