Trim the root ends and most of the greens from the leeks. Cut them lengthwise, rinse well under cold water and slice thinly. Put them in a colander and rinse again. Drain thoroughly.
Peel the squash. Cut in half, scrape out the seeds and cut into 1-inch chunks. You should have about 4 cups of squash.
Core and chop the pear and/or apple. Peel and dice the ginger. (You can use a spoon to remove the skin of the ginger.) Grind or coarsely chop fennel seed.
In a large soup pot over medium heat, place 2 tablespoons butter, Earth Balance or olive oil. Add the leeks and saute until softened, about 3-4 minutes.
Add the squash, pear(s) and/or apple, ginger, fennel seed, salt and 5-6 cups of water to the stockpot. You want the water to cover the vegetables.
Increase the heat and once the water boils, reduce the heat so it simmers. Cook until the vegetables are soft and crush easily against the side of the pot, about 25-40 minutes.
Puree the soup until it is smooth, leaving a few chunks for texture. If it is too thick, thin it with either apple cider or a little bit of water. Taste and season with salt and pepper.
To serve, fill a bowl with soup and garnish with a dollop of creme fraiche, sour cream or plain yogurt and a sprinkling of cinnamon or toasted pumpkin seeds, if desired.