Prep. Line a baking dish with parchment paper. Lightly butter the parchment paper.
Brown the butter. Add the butter to a Dutch oven or large stock pot set over medium-low heat. Melt the butter and let it turn a light golden brown color.
Make the marshmallow mixture. Swirl the butter in the pan and then add one and a half bags of marshmallows. Stir until the marshmallows are completely melted but not entirely smooth. Remove from the heat.
Fold in the crispy cereal. Add the crispy rice cereal, the vanilla, the salt, and the remaining half bag of marshmallows, and stir until the cereal is coated with the melted marshmallow mixture.
Transfer to baking dish. Pour the mixture into the prepared baking dish. Lightly grease a rubber spatula and spread the mixture into the baking dish, gently pressing the crispy treats with the back of the spatula to secure them in the pan without pressing them flat.
Rest, cut, and serve. Allow the Rice Krispie treats to set in the pan for about 1 hour. Then lift them from the pan using the ends of the parchment paper. Cut into individual pieces and serve.
Notes
Storage Tips
To store. Rice Krispie treats are best enjoyed within two days of making them. Store in an airtight container at room temperature for best results.To make ahead. Prepare, cut, and wrap well in an airtight container. Store at room temperature and serve within two days of making them.To freeze. Cool completely, cut, and wrap each treat individually with parchment paper. Then wrap with plastic wrap and store in an airtight, freezer-safe container. To serve, remove all or individual treats from the freezer and allow them to thaw. Unwrap and serve.