Butternut Squash Soup

This is really good.  We have a missionary that has PKU in our area right now - so he cannot have protein.  I am always trying to find recipes that are tasty and full of vegetables and fruits.  This is actually from America's Test Kitchen Magazine and worth the trouble. 

Butternut Squash Soup
2 1/2 pounds butternut squash, peeled, seeded and cut into 2 inch pieces.
2 Tablespoons butter
1 leek, white and green parts only, quartered lengthwise, sliced and washed thoroughly (about 1 1/2 cups)
Salt and pepper
4 cups vegetable broth
1-2 cups water
2 sprigs fresh thyme
1 bay leaf
Pinch cayenne pepper
Sour cream or butter
Place squash in a bowl, cover and microwave until paring knife glides through flesh, 14-18 minutes, stirring halfway through the process.  Carefully transfer to colander that is set in a bowl (squash will be very hot) and drain for at least 5 minutes; reserve liquid.

Melt butter in Dutch oven over medium-high heat.  Add squash, leek and 1 teaspoon salt; cook, stirring occasionally; until squash pieces begin to break down and brown fond forms on the bottom of the pot, 10-15 minutes.

Add 2 cups broth and scrape bottom of pot to loos and dissolve the fond.  Add remaining 2 cups of broth, reserved squash liquid, 1 cup water, thyme sprigs, bay leaf and cayenne.  Increase heat to high, bring to a boil and then reduce to a simmer.  Simmer over medium low heat for 10 minutes or until leeks are fully tender.

Remove and discard the bay leaf and thyme sprigs.  Working in small batches, process the soup in blender until smooth, 1-2 minutes (You might have to add a bit of water if soup is too thick).Return soup to clean pot and bring to simmer, thinning with up to 1 cup water to desired consistency.  Season with salt and pepper to taste and dollop of sour cream or butter in each bowl.  (Soup can be made two days in advance).