Gather your ingredients: unsalted butter, mini marshmallows, gluten-free rice cereal, vanilla extract, and a pinch of salt.
In a large saucepan, melt the butter over low heat. Once melted, add the mini marshmallows and stir continuously until completely melted and smooth. Remove from heat.
Gradually pour the gluten-free rice cereal into the melted marshmallow mixture, stirring gently until every piece is evenly coated.
Lightly grease a 9x13-inch baking dish. Pour the marshmallow and cereal mixture into the dish and press down firmly to create an even layer.
Allow to cool at room temperature for 30 minutes. Once cool, cut into squares and enjoy.