Preheat your oven to 350 degrees Fahrenheit.
Prep mushrooms by removing stems and gills, and removing any dirt or debris.
Put the stems to the side.
Finely chop up the stems of the mushrooms, and one of the cleaned caps.
Stir pumpkin into the spice mixture in a medium sized bowl, and mix until thoroughly combined.
Add in walnuts and the finely chopped mushrooms and mix until uniform.
Divide up filling and portion out into the remaining five mushroom caps.
Bake for 30 minutes, or until the caps have shrunk in size and everything is tender.
Let cool and enjoy!