Boil sliced squash and onion in salted water until tender, drain, mash and set aside.
Melt 1 stick of butter, add the seasoning packets from the stuffing mix, and then stir this mixture into the stuffing cubes making the mixture moist. (I put 1 and 1/2 sticks of butter in the ingredients because 1 stick doesn't make it moist enough for me, but some people may think it is enough.)
Mix the sour cream and soup and then add to the squash and onion. (Sometimes I add a cup of shredded cheese to this mixture also)
Gently fold the squash mixture into the stuffing mixture.
Spread the dressing into a prepared 9x13 dish and make a loose tent over the dish with aluminum foil.
Bake @ 350 degrees for approx 30 minutes. Remove foil and bake approx 10 more minutes or until golden and bubbly.