Peel the pumpkin if you want. You can easily leave the skin on. I do this often. Especially when using red-skinned pumpkin like the Kuri squash. Remove the pumpkin guts and reserve the trim and guts to make pumpkin stock used in other preparations.
The key is to chop up the pumpkin as small as you can for it to cook as quickly as possible. This is a secret little Michelin restaurant law we had when I worked in London. When you chop it up fine and cook it quick the flavour peaks and you have a vibrant coloured puree that taste as great and as pumpkiny as it possibly can. Never boil it in water or microwave it.
Boiling in water diminishes the gentle flavour. Microwaving does not get rid of the water in the pumpkin for it to concentrate the flavour while also cooking it at the correct speed(cooks too quickly and burns before it's at it's best). Baking or roasting takes too long and is more suitable for when you want to make pumpkin salad. So, the best way is to cook it in a pot or pan with the lid on. Stirring often and adding a small drop of water now and again to stop it from burning. This takes about 5 minutes given that you are using the correct sized pot or pan and also chopped the pumpkin small enough. I used a 2-litre saucepan for this recipe and 400g of chopped pumpkin.
When the pumpkin is soft(test this by tasting it), it can be blended. Blend until smooth and let it cool down before using in pumpkin cream cheese spread, pumpkin bread or pumpkin cake among others.
Keep the skin on if it's a red-skinned pumpkin. It will give the puree a vibrant colour and add to the flavour.
Store in the fridge for up to 5 days closed airtight or for up to a year in the freezer.
If you want a deeper more complex flavour simply add a touch of oil to the pumpkin and caramelise it before adding water bit by bit.
You can season the puree with salt, sugar or spices depending on how you want to use it. I find that keeping it plain until you decide what to cook with it, is the best option. That way you can go either way. Sweet or Savoury.