In a medium sauce pan over medium heat, melt your butter
Next add your pumpkin puree and marshmallows to the pot and keep stirring until the marshmallows are completely melted
Once the marshmallows are melted, turn off the heat and add your rice krispies and keep stirring until all of it comes together
Pour your mixture into your pan and take a piece of plastic wrap and place over top and press down your rice krispie mixture until it is all even on top