​Hearty Butternut Squash Soup

From Cook's Illustrated, here's another fall favorite, a good soup to stock up in the freezer.
Soup:
1 2 to 2 1/2 lb butternut squash
4 cups chicken broth
3 cups water
4 tbsp unsalted butter
1 tbsp soy sauce
1 tbsp vegetable oil
1 lb leeks, white and light green parts only, halved lengthwise, sliced thin and washed thoroughly
1 tbsp tomato paste
2 garlic cloves, minced
salt and pepper
3 15-ounce cans canellini beans
1 tsp white wine vinegar

Sage Pesto garnish:
1/2 cup walnuts, toasted
2 cloves garlic, minced
1 cup fresh parsley leaves
1/2 cup fresh sage leaves
3/4 cup extra-virgin olive oil
1 ounce Parmesan cheese, grated (1/2 cup), plus extra for serving
​salt and pepper
For the soup:
Using a vegetable peeler, peel the squash to remove the outer rind and the fibrous threads just below; peel until the squash is completely orange, and no white flesh remains. Cut the round bulb section off teh squash and cut in half lengthwise. Scoop out the seeds, then cut each half into four wedges. 

Bring wedges, broth, water, butter and soy sauce to a boil in a medium saucepan over high heat. Reduce heat to medium, partially cover and simmer vigourously until the squash is very tender and starting to fall apart, about 20 minutes. Mash squash in broth until completely broken down. Cover to keep warm.

Meanwhile, cut the neck of teh squash into 1/3-inch pieces. Heat oil in a large Dutch oven ocer medium heat until shimmering. Add leeks and tomato paste and cook, stirring occasionally, until the leeks are softened and the tomato paste has darkened, about 5 minutes. Add garlic and cook, stirring, until fragrant, about 30 seconds. Add squash pieces, 3/4 tsp salt adn 1/4 tsp pepper and cook, stirring occasionally, for 5 minutes. Add squash broth and bring to a simmer. Partially cover and cook for 10 minutes. 

Add beans and their liquid, partially cover, and cook, stirring occasionally, until squash is just tender, 15 to 20 minutes. Stir in vinegar and season to taste with salt and pepper. Serve, passing garnishes separately. 

For the pesto:
Pulse walnuts and garlic in a food processor until coarsely chopped, about 5 pulses. Add parsley and sage; with processor running, slowly add oil and process until smooth, about 1 minute. Transfer to a small bowl and stir in Parmesan. Season with salt and pepper. 
Source: Cook's Illustrated, November & December 2016