I would nuke it, puree it in a food processor and then freeze it in ice cube trays. Put as many or as few "cubes" into your soup and enjoy.

Why not just put chunks of the raw squash into your soup? It'll cook when the soup does.
You can also cook the squash, it will taste better if you roast it instead of mircowaving, freeze the chunks in a bag and pop some into your soup.

Carefully cut the squash in half, remove the seeds and fiber string-thingies; place cut side down on a greased baking sheet and bake at 350 until a knife tip easily pierces the skin; cool, scoop out the cooked flesh, puree, and freeze in the ice cube tray or small containers.

But I usually go ahead and make my yummy butternut squash soup, then freeze the soup in serving portions. But I prefer not to add extra vegetables to the soup that has onion and apple in it.

Teresa

I agree, cook the squash and puree it, then add to soup as you wish. You can also add it to yeast breads, use it in place of pumpkin for quick bread or pies or custard and as Teresa mentioned, it makes pretty good soup on its own. I also make a ravioli filling out of butternut squash.

I add kale to bean soup for a "Tuscan" bean soup, but I like kale and other greens. I also made a pasta that Elery liked (but I did not, particularly), with sauteed kale, Italian sausage, pasta and parmesan.

I have a homemade noodle recipe that takes basil, I think greens like spinach or kale would work quite nicely in that too.

I like nearly all vegetables, though, so I'm not particularly adept at hiding them.

Annie