Trim tips off of thawed asparagus spears; set aside.
Chop asparagus stalks and place in medium saucepan. Add chicken stock and bring to a boil over medium-high heat. Reduce heat and simmer for 8 minutes. *Transfer asparagus and stock to a blender and puree until smooth. Work in batches, if necessary. (TIP: To avoid spilling, cover blender with dish towel and pulse.)
Set mesh strainer over saucepan and pour asparagus puree into it, if desired, or return puree to saucepan. Add white sauce and whisk until smooth. Bring to a simmer over medium-high heat. Reduce heat to low and add cream and reserved asparagus tips. Heat soup through and adjust seasoning with salt and pepper.
* When blending hot liquids: Remove liquid from the heat and allow to cool for at least 5 minutes. Transfer liquid to a blender or food processor and fill it no more than halfway. If using a blender, release one corner of the lid. This prevents the vacuum effect that creates heat explosions. Place a towel over the top of the machine, pulse a few times then process on high speed until smooth. .
Recipe courtesy of Sandra Lee, 2008