Preheat the oven to 400º F. Peel and cut the butternut squash into 1/4 inch cubes. (Note: It is easiest to cut the squash in half, discarding both ends, and then peel the skin with a vegetable peeler. Then, take the two peeled pieces and cut in half length-wise. Make sure to scoop out all of the seeds and pulp before dicing.)
Place the cubed squash into a large mixing bowl and toss it with the 1/4 cup of extra virgin olive oil, salt, pepper, and nutmeg, making sure all of the pieces are coated generously. Arrange the mixture into two 9” x 13” baking pans.
Place the squash in the preheated oven and roast for 45 minutes to one hour. The squash should be fork-tender and slightly browned. (If the squash starts to brown too soon into the cooking time, make sure to turn the pieces around in the pan and/or lower the oven temperature to 375º.)
While the squash is roasting, cut off the root end and the green portion of the leeks and discard, or save for another use. Take the white portion and slice vertically down the length of the leek, and then into 1/4 inch slices. Place the leek slices into a large bowl of cold water, toss a little with your hands to rinse them, and then set aside.
Chop the onions into a 1/4 inch dice and place into a 6-qt. stockpot. Add in the remaining 2 Tbsp of olive oil and heat the onions on medium-high heat until translucent, stirring occasionally.
Using your hands, transfer the leeks from the bowl of water into the pot with the onions. (Try not to strain the leeks by pouring them out of the bowl, as all of the dirt will have sunk to the bottom.)
Toss the leeks with the sautéeing onions and then add in the 2 Tbsp of butter. Stir the mixture occasionally. Once the squash is cooked, carefully scoop the cooked squash into the pot on top of the cooked onions and leeks. Pour half (2 cups) of the chicken or vegetable stock into the pot and stir the mixture. Reduce the heat to low and simmer for about 20 minutes. Using a handheld immersion blender*, carefully liquify the mixture, making sure all of the lumps and vegetable pieces are well blended. Stir in the remaining 2 cups of stock.
Stir in the Hood Sour Cream and continue to simmer on low until ready to serve.
Serve in soup bowls and garnish with a generous scoop of Hood Sour Cream.
* If you don't have an immersion blender, you could also purée the soup using a food processer or blender. Ladle the soup mixture in batches, being careful to let the mixture cool slightly before blending.