Preheat the oven to 425 degrees
Wash any dirt off of the butternut squash and split it lengthwise
Scoop the seeds out of the squash
Brush the squash with olive oil
Place the squash, cut side down, on a baking sheet and bake until brown and soft to the touch - about 40 minutes
Let the squash cool slightly and scoop the flesh out of the skin
Chop the onion (or onions)
Chop the leek (if using)
Chop the garlic
Chop the first 8 leaves of sage and strip the thyme leaves off the stem (or measure the dried herbs)
Heat a tablespoon of olive oil in a large pot
Add the onions, leeks (if using), sage, thyme, salt and pepper to the pot and saute until the onions begin to soften - about 10 minutes
Add the garlic and sauté for another 30 seconds
Add the squash squash and 6 cups of vegetable broth to the pot. (You may need to add more as it cooks to get the consistency you like in the soup)
Stir the soup, smoothing the squash with a spoon, and bring to a boil
Reduce the heat and simmer for 20 minutes
Grab your handy, dandy immersion blender (or regular blender)
Blend the soup until it's smooth and a consistency you like, adding more broth as necessary. Adjust the seasonings to your taste - I often find it needs more salt at this point, especially if I use low sodium broth