Tip: To clean leeks, trim and discard green tops and white roots. Split leeks lengthwise and place in plenty of water. Swish the leeks in the water to release any sand or soil. Drain. Repeat until no grit remains.
To make ahead: Cover and refrigerate the bisque and the crouton topping for up to 3 days.
2 starch, 2 vegetable, 1 fat, 1/2 fat-free milk