1 stick butter, divided
1/2 whole onion, finely diced
1 whole carrot, finely diced
1 stalk celery, finely diced
1 whole (to 2 whole) cauliflower heads, roughly chopped (I halved the recipe and used about 3/4 of a head of cauliflower)
2 Tblsp fresh or dried parsley
2 quarts low-sodium chicken broth or stock
6 Tblsp. all-purpose flour
2 cups whole milk (I used 2% to cut a little fat, and it was delicious...next time I may try 1%)
1 cup half-and-half
2 tsp. to 4 tsp. salt, to taste (I omitted this, and just added a little to our own bowls of soup)
1 cup (heaping) sour cream, room temperature
In a large soup pot or dutch oven, melt 4 Tblsp. butter. Add the onion and cook for a few minutes or until it starts to turn brown.
Add the carrots and celery and cook an additional couple of minutes. Add cauliflower and parsley and stir to combine.
Cover and cook over very low heat for 15 minutes. After 15 minutes, pour in chicken stock and bring to a boil, then reduce heat and allow to simmer.
In a medium saucepan, melt 4 Tblsp. butter. Mix the flour with the milk and whisk to combine. Add flour-milk mixture slowly to the butter, whisking constantly. It should thicken up fairly quickly.
Remove from heat and stir in 1 cup half-and-half. Add mixture to the simmering soup. Allow to simmer for 15 to 20 minutes. Check seasoning and add more salt or pepper if necessary.
Before serving, place the sour cream in a serving bowl or soup tureen. Add two or three ladles of hot soup into the tureen and stir to combine with the sour cream. Pour in remaining soup and stir.
Serve immediately.