The first evening I served this at a dinner party, the only thing I regretted was that I didn't make more. This is delicious and easy. In a nutshell, you roast squash in the oven... easy... spread some yogurt on a plate... easy... then drizzle it with some dressing... easy! The skin is really good if you want to eat it but some people prefer to scrape the squash out of the skin.
Heat 6 tbsp of butter in a sauce pan over medium heat and cook it until it gets frothy and a tiny bit brown – swirl it around once in awhile. As soon as it is slightly brown, remove it from the heat and add the remaining ingredients.
This can be made in advance. Warm it slightly before you use it so it get nice and runny again.
If I was to do two squash for a larger group - I may only 1.5 times the butter and yogurt - I don't think it would be necessary to double those components. Also, the squash really just has to be warm so if you are trying to time several dishes, it's OK if the squash has to sit out of the oven for a few minutes before serving.