Broccoli Cheese Soup

We've made this a few times and the blog I originally got the recipe on disappeared so I figured I better get the recipe down for us.  We all like this soup--it's super healthy and tastes so much better than it sounds!  We like to have homemade bread or breadsticks with it.


BROCCOLI-CHEESE SOUP
(I saw it on America's Test Kitchen and then found a blog which already wrote out the recipe for me, found here)

Ingredients
2 T unsalted butter
2 pounds broccoli florets (could possibly use frozen)
1 medium onion, roughly chopped (about 1 cup)
2 medium garlic cloves, minced or pressed through a garlic press
1 1/2 t dry mustard powder
pinch of cayenne pepper
table salt
3-4 C water
1/4 t baking soda
2 C low-sodium chicken broth
2 ounces baby spinach
3 ounces sharp cheddar cheese, shredded (3/4 cup)
1 1/2 ounces Parmesan cheese, grated fine, plus extra for serving

Directions:
Heat butter in a large Dutch oven over medium-high heat. When foaming subsides, add broccoli, onion, garlic, dry mustard, cayenne, and 1 teaspoon salt. Cook, stirring frequently, until fragrant, about 8 minutes. Add 1 cup of water and baking soda. Bring to a simmer, cover, and cook until broccoli is very soft, about 20 minutes, stirring once during cooking.

Add broth and 2 cups of water and increase heat to medium-high. When mixture begins to simmer, stir in spinach and cook until wilted, about 1 minute. Transfer half of soup to blender, add cheddar and Parmesan, and process until smooth, about 1 minute. (Be sure to hold the lid on tight when blending warm liquids!)Transfer soup to a medium bowl and repeat with remaining soup. Return soup to the Dutch oven, and place over medium heat and bring to a simmer. Adjust consistency of the soup with up to 1 cup of water. Season to taste with salt and pepper.

Can serve with cheddar cheese, parmesan or croutons if desired.