Creamy Potato & Leek Soup

4 medium leeks, white & green parts halved lengthwise, washed, & sliced thin (about 4 c), dark green parts halved, washed, & cut into 2-inch pieces
2 C Vegetable or chicken broth
2 C Water
4 Tb butter
1 C chopped onion
¼ tsp. salt
1 small russet potato (6 oz.) peeled, chopped
1 bay leaf
1 (4 in.) sprig fresh thyme
1 large slice white bread, lightly toasted & torn into ½ inch slices
Pepper to taste
½ C Half & Half or cream (opt.)

Bring dark-green leek pieces, broth, and water to boil in large saucepan over high heat. Reduce to low, cover, and simmer 20 min. Strain broth through fine mesh strainer into a bowl, pressing on solids to extract liquid; set aside. Discard solids in strainer and rinse out saucepan. Melt butter in now empty pan over med-low. When foamy, add sliced leeks, onion, and salt. Cook and stir over low until vegetables are softened. Over high heat, stir in reserved broth, potato, bay leaf, and thyme sprig and boil. Reduce to low, simmer until potatoes are tender. Add toasted bread and simmer until bread is completely saturated and starts to break down, about 5 minutes. Remove and discard bay leaf and thyme sprig. Add cream (opt.) Transfer soup to blender and process until smooth and creamy, 2-3 minutes. Season with salt and pepper.