The ingenious thing about this recipe (beside it being a mash–up of two childhood favorites) is that the Rice Krispies treats mimic the texture of waffle cones. Be sure to use premium quality ice cream because it's churned with less air, which makes it melt more slowly.
Line a 17-by-12-inch baking sheet with parchment or a silicone mat. In a large microwave safe bowl, melt the butter. Add the marshmallows and chopped cookies and cream chocolate bar and stir to combine.2.
Microwave on high power for 1½ to 2 minutes, until puffed and melted. Stir until smooth.3.
Stir in the rice cereal and chopped Oreo cookies and press into the baking sheet, using lightly moistened hands. Using a straight edge and pastry wheel, trim 1/2-inch from the short sides. Then cut the cake in half, forming two 8-by-12-inch pieces.4.
Using the straight edge and cutter, lightly score one piece into 16 bars, cutting about 1/4-way through.5.
Scoop the ice cream onto the un-scored half and spread evenly.6.
Top with the other half, scored-side up and press lightly to compact. Freeze until firm, about 4 hours, then cut between the score marks into bars.7.
Return to the freezer or serve.
Grace Parisi is a New York City-based food writer, cookbook author and food stylist. Her book, Get Saucy, was nominated for a James Beard award. Her latest book, Quick Pickles comes out in Spring 2016. Follow her on Instagram and Twitter.