Preheat oven to 350. Cut butternut squash in half lengthwise, scoop out seeds, drizzle with olive oil and a sprinkle of salt, and lay face down on lined baking sheet. Cook until a fork is inserted easily into the skin, about 20 minutes. Remove and allow to cool.
Meanwhile, in stockpot, melt butter and remaining oil. Add chopped onion and celery and cook until translucent. Add garlic and chopped apple, and cook until garlic is fragrant and apple is tender.
Pour in stock and dry seasoning (nutmeg, cinnamon, salt and pepper) and give a few minutes to simmer.
Taking the squash, scoop out the inside and add to the stockpot. Stirring well, this should blend the flavors. Turn heat very low and allow to meld.
Carefully using the immersion blender, puree soup until it has a creamy consistency.
Add in finely chopped sage leaves and heavy whipping cream and simmer on low until flavors join, tasting and stirring often.
Serve immediately with a sage leaf for garnish. Enjoy!Variation: often when I make butternut squash soup, I throw a tsp of curry powder in as well. If you prefer a bit more savory than sweet, lesson the amount of cinnamon and nutmeg and add a dash of curry powder!