So, as you will probably be able to tell from what is about to follow, I am not very good at making this right now, but I feel that the basics of this dish down and this recipie should serve as a starting point for experimentation into this sort of thing.
The first thing that you will want to do is preheat your oven to some random temperature, I'm not convinced it matters I just pressed the up button several times. Then you will chop your pumkin in half and realize that taking the seeds out is much easier if you aren't trying to use the punkin as a decoration. After your seeds are out you'll cut the halves into wedges, put them in a baking pan and drizzle olive oil onto them along with some salt and pepper or something and stick it in the oven. I guess if you wanted you could roast some of the other vegetables you were going to put in the soup in the oven with the pumkin but I didn't think that far ahead.
After putting your pumkin in the oven you'll realize that it will have to be in there for at least an hour so you'll take the pumkin seeds, wash them off, throw them into a frying pan with a bunch of olive oil, cook them to your liking, season them with garlic salt then eat them all. After that you will drive to the grocerey store to buy all the other ingreedients that you forgot about.
Upon returning from the store with the rest of the required ingredients you will accidentially turn off the oven as you are checking on the pumkin. The pumkin should be soft and somewhat carmelized. After sitting on the couch for ten minutes you will get up to check on the pumkin again, realize that you accidentially turned the oven off ten minutes ago and decide that there is not time like the present to start dealing with the rest of the stuff so you will take the pumkin out of the oven to cool.
While your pumkin is cooling chop up your onion and throw it in a pot with some olive oil and garlic. It really doesn't matter how big your onion pieces are chopped because you will throw it all in a blender anyways. Cook the onion until it is translucent. This is the point where you mean to add spices and things, but you'll accinentially skip that step and throw the pumkin in the pot instead.
Turn the stove down so you don't burn your onion then take a spoon to scoop the pumkin flesh out of the skin and plop it into the pot. You will shortly realize that the soon wasn't as effective as you had hoped and then switch to just using your hands. When all the pumkin flesh is in the pot you can stir it arround a bit and realize that you forgot to put in the spices earlier so you'll throw some in (I put in some nutmeg and cinnamon because those seemed pumkiny, I meant to put in some thyme but there was no price tag on it at the grocerey store when I was there and I didn't feel like paying $??.99). Once you've stired that around a bit and decided those flavors have gotten to know eachother you'll look for your misplaced can opener to open your chicken broth can.
You'll start pouring in your chicken broth a little bit at a time because you are not sure how much you really need since you don't want your soup to thin, but you will eventually just decide to dump the whole thing in. You'll let that simmer a bit and relize that you had a carrot you meant to put in so you'll chop it up and throw it in realizing that you should have done that when you only had onions in the pot. You'll then let that simmer until you get bored of that and then take it off the heat and dump it all into a blender, (or in my case a magic bullet I borrowed from my sister) blend it up and serve.
After understanding this process you should feel free (and obligated) to experiment with different flavors and processes because whatever you end up with won't be perfect, but with trial and error you may get close.