This recipe is from Aeri of Aeri's Kitchen (http://aeriskitchen.com/), with a very slight adaptation. Though the name Hobakjuk means Pumpkin Porridge, you can use any seasonable winter squash, just make sure it's about the same weight and you check it during the roasting period.
Substituting canned pumpkin (not pumpkin pie filling!) is possible but not recommended. It's also possible to boil the squash instead of oven roasting, but doing so will mellow the squash flavor.
Finally, you can use less water in the blender step if you want a stronger flavor from the squash, but consider adapting how much slurry you put in as this will also make it a bit thicker.