First you'll want to butter the bottom and sides of a 9x9 inch baking dish.
Next we're going to prepare our pumpkin by removing some of the water so we get the flavor but not the moisture. Spread your pumpkin puree out on a stack of paper towels and allow to sit for about 5-10 minutes. The paper towels will draw out the water, you'll see a ring of wetness around the pumpkin. When you are ready to use it you can easily scrape the pumpkin off of the paper towels.
Then in a large saucepan melt butter over medium heat stirring frequently. Add in pumpkin and continue heating and stir until well mixed.
Next add in marshmallows and continue heating, stirring frequently until marshmallows are melted, and everything is well mixed.
Then add in pumpkin pie spice and stir in until evenly mixed. If a deeper orange color is desired add a few drops of orange food coloring.
Remove the pan from the heat and fold in rice krispie cereal until evenly coated.
Evenly press the rice krispie mixture into prepared pan. I like to do this with my hands, I coat them with a light coating of butter and then press the mixture into the baking pan. You can also a piece of wax paper to protect them or use a spatula.
Set the pan aside to cool.
While the rice krispies mixture is cooling place white chocolate chips in a double boiler, or a heat safe bowl over a small pot of water. Heat over medium high heat stirring frequently until melted and smooth. You can also melt your chocolate in the microwave, place it in a microwave safe bowl and heat in 30 second increments stirring between each until the chocolate is melted.
Allow the chocolate to cool a little before handling, then place in a piping bag or zip top bag with the corner cut off. Gently squeeze and drizzle the melted chocolate over the top of the treats. I drizzled my chocolate over the whole pan but you can also cut the treats and drizzle over individual treats.
Let cool completely, cut into 9 squares and serve.
Store treats in an airtight container.