Chop the onions and celery. Thinly slice the carrots.
In a 6- to 7-qt pot, heat the oil on medium. Add onions and celery. Season with salt. Cook 8–10 min., until almost tender, stirring often.
Add carrots and the butternut squash. Cook 5 min., stirring occasionally. Add the wine. Heat to a simmer and simmer 2–3 min., until slightly reduced.
Add the broth. Heat to a boil on high. Reduce heat and simmer 20–25 min., until carrots and squash are very tender.
Remove soup from heat. With immersion blender or in batches in regular blender, purée soup until smooth. When ready to serve, heat purée on medium and whisk in the half & half. Season with salt and pepper to taste. Divide among bowls. Garnish with the chives.
UPGRADE: Stir together a bit of sour cream and half & half until slightly runny. Swirl into each bowl of soup before adding chives.