(Note - using a jackolantern pumpkin that has been previously carved is dangerous - it has been exposed to all kinds of things, not to mention growth of bacteria from exposure to air, that can make you sick - use a whole pumpkin that has not been mutilated in any way!!).
Let your roasted pumpkins cool until they are cool enough to handle. Then scrape out the soft flesh into a bowl and cool completely. Whirl in your food processor for a couple of minutes until it is smooth and silky. Refrigerate until ready to use (you can make this up to two days in advance if keeping in the fridge, or you can freeze it for longer periods).
Pumpkin Pie with Streusel Topping
Four Layer Pumpkin Cake
You could also substitute this pumpkin puree for any roasted squash in soup recipes! It would sub in great for butternut or acorn squash.