Step 1: First, line an 8″ x 8″ baking pan with parchment paper. In a large pot, melt the butter and pumpkin puree together over medium heat.
Step 2: Add the marshmallows and vanilla extract and turn the heat down to low. Stir the mixture until the marshmallows are completely melted.
Step 3: Now remove the pot from the heat and fold in the cereal. Make sure each piece of cereal is coated with the marshmallow mixture.
Step 4: Transfer the mixture to the prepared baking pan. Gently spread the mixture to fit the pan and press it down lightly so you have an even layer. Allow the treats to set for at least 1 hour at room temperature.