I use pie pumpkins (smaller ones). I really don't know if this would work with a regular large pumpkins, I have never tried it.
To make pumpkin puree, you will need:
Preheat oven to 350 degrees F
Cut the tops off the pumpkins as close to the stem as possible. I find it much easier to use a serrated knife.
Place in oven for approximately 30 minutes, until flesh is soft. This may take more time, depending on the size of your pumpkins.
Now I am going to go make a pumpkin banana cake... recipe coming soon! :)