Preheat the oven to 400 degrees F (200 degrees C). Line a large baking tray with parchment paper.
Wash a pumpkin well with water as we are going to cook it with the skin on. Cut it in half using a sharp knife. If the pumpkin is very large, then cut the halves further into halves.
Scoop out the seeds using a large spoon.
Place the pumpkin pieces on the baking tray with the cut side up.
Place the tray in the middle rack of the oven and bake for 50-60 minutes until the flesh is tender and a fork easily slides in.
Remove the tray from the oven and let the pumpkin cool down for 40-50 minutes. Scoop the flesh using a large spoon and discard the skin.
Add the flesh to a blender or a food processor.
Puree until smooth. Puree in batches if your food processor is not big enough and keep scraping the sides a few times while blending. Store the puree in an airtight container and use it as required.
Line the tray with parchment paper to avoid pumpkin pieces from sticking to the tray.If your puree is not as thick as the canned puree, then let it sit in a fine-mesh strainer for 25-30 minutes. The extra liquid will drip down and you will get a thick puree.You can make the puree using a mix of squash and pumpkin.