I like to add a couple of steps to my butternut squash soup. I split the squash open lengthwise, oil them, spice them up with whatever I'm in the mood for (cumin, cinnamon, coriander, cayenne, allspice), brush a little maple syrup over them, and roast them for a while. How long? It depends. I once accidentally roasted them to the point where they had almost completely dried up; it was the best butternut squash soup I'd ever made! After the roasting you proceed as usual, with the mirepoix, add the squash, you may deglaze with a little Cognac or what not. Add vegetable or chicken stock, cook til soft and puree.
I don't add cream or milk in my soup. I find it is rich enough as it is, and I like to give my guests room for the rest of the meal. The roasting with the spices and maple brings out a whole other depth of flavour which I think you will enjoy.