Line a square baking pan (8x8”/20.3cm x 20.3cm) with overlapping sheets of parchment paper. Set aside.
Place the marshmallows in a large bowl, then top with pieces of butter.
Microwave in 30-second intervals, continuing until the butter is melted and the marshmallows puff up.
Using a rubber spatula, stir the butter and marshmallows together, then add the vanilla extract and stir again.
Pour in the rice cereal, and fold it in with a rubber or silicone spatula. Once the cereal is evenly coated in the marshmallow mixture, you’re ready for the next step.
Transfer the rice cereal mixture to the prepared baking pan, and spread it out in an even layer.
Loosely cover and allow to rest at room temperature for at least 1 hour.
Using the sides of the parchment paper lining, carefully remove the treats from the baking pan and slice them into 9-12 squares.
Stovetop:
Add the marshmallows and butter to a very large pot. Heat over medium-heat on the stovetop, stirring often until melted and well combined.
Remove the marshmallows from the heat and stir in the vanilla extract.
Pour in the cereal, gently folding it into the melted marshmallow mixture until evenly coated.
Transfer to the prepared baking pan, spreading it into an even layer.
Loosely cover and allow to rest at room temperature for at least 1 hour.
Remove the treats from the baking pan and slice them into 9-12 squares.
Notes
Storing: Cereal treats can be stored at room temperature in an airtight container for up to 3 days. For the best results, store the treats between layers of parchment paper to prevent sticking. Treats can be stored in the refrigerator, but will develop a dense texture so room temperature is recommended.*Finding gluten-free rice cereals: The brand name “Rice Krispies” is not gluten-free, as it contains barley (which contains gluten). Due to their high risk of cross-contamination, cereals should be labeled as gluten-free and manufactured in a dedicated facility (or dedicated lines). In the US, there are more options for gluten-free rice cereals, but in Canada and other countries, the choice is limited. We like to use Nature’s Path Crispy Rice Cereal (be careful, as one of their rice cereals contains gluten, but one does not), which is labeled as gluten-free. Use whatever you have available to you that is also certified gluten-free.Note about cross-contamination: If cross-contamination is a concern, use only ingredients that are verified and certified gluten-free, and prepare them using tools and equipment that are never used to prepare gluten-containing foods.