Step 1: Grease a 13"x9" baking pan with butter. In a large pot over medium heat, melt the butter. Add marshmallows and salt, stirring until melted and smooth. Continue cooking until marshmallows turn slightly golden, about 5 minutes more. Remove from heat and stir in Rice Krispies.

Step 2: Pour the mixture into the prepared pan and smooth the top without packing the Rice Krispies too tightly. Let it cool completely before slicing and serving.