Step 1

Butter a 9x13-inch baking dish or line with a parchment paper sling.

Step 2

Melt the butter in a large pot over medium heat.  Add the cookie butter and all but 2 cups of the marshmallows and stir until both are melted and smooth.  Remove from heat.

Step 3

Add the Rice Krispies cereal, Biscoff cookies, and remaining 2 cups of marshmallows and stir until combined.

Step 4

Gently press into the prepared pan.  It helps to use the wrappers from the butter to press down rather than the sticky spoon used to stir the rice krispie treats.  Refrigerate for 15-30 minutes to help them set up and cool down.

Step 5

Make the cookie butter glaze by combining the two tablespoons of melted butter with the remaining 1/2 cup of cookie butter and stirring until smooth, then spreading evenly over the cooled rice krispie treats with a spatula.  Refrigerate for another 15 minutes to help the glaze set a bit.

Step 6

Slice into bars and devour!