I roasted a butternut squash for this and cooked my own beans because that's what I had on hand. I've modified the recipe to take advantage of convenience foods. Canned beans and frozen squash puree should be just fine in this recipe and yield a similar quality of finished result.
The leeks just make this. Onions can be used if you can't get your hands on leeks. But do try to get leeks.
1 package frozen butternut squash
2 leeks, white and pale green parts only
1 tablespoon butter
2 tablespoons sherry vinegar or other full-bodied, flavorful vinegar
1 can of pre-cooked white beans
1/4 cup heavy cream
2 cups chicken or vegetable stock
Handful of greens such as spinach or beet greens (optional)
salt and pepper to taste
Microwave squash puree per package directions. Meanwhile, chop leeks and add to large saucepan with butter, and a teaspoon of salt. Sautee leeks on low heat for 5-10 minutes until soft and just starting to brown. Turn off heat and add the sherry vinegar. Stir briefly so the onions absorb the vinegar.
Add 2 cups stock to onions, stir. Drain can of beans, add to pot. Add thawed squash puree. Add greens if using. Stir to combine. Turn heat to medium and simmer for 5-10 minutes, stirring occasionally, until soup is combined and greens are tender. Taste and add more salt if needed. Turn off heat and stir in cream. Serve with crusty bread or croûtons if desired. Serves 4.