In a large saucepan combine butter, marshmallows, and pumpkin puree. Heat over a medium heat while stirring, until the butter and marshmallows are completely melted and well combined.

Remove from the heat and add in the vanilla, and pumpkin spice and stir to combine.

Let the hot mixture stand for about 20 min. Allowing it to cool before adding the rice cereal will help them from becoming too soggy. After 20 min. stir in the rice krispies until completely combined.

Spray a 9 x 13 inch pan with nonstick cooking spray and then pour the cereal mixture into it. Use a rubber spatula sprayed in nonstick cooking spray to smooth out the mixture. Allow to set and then cut the crispy rice treats into squares or triangles with a sharp knife.

Optional: Add a white chocolate drizzle and pumpkin sprinkles