Broccoli Cheese Soup

(From Cook's Illustrated)

Oh I know, yet another blended soup - you'd think I'd be tired of them by now, but apparently not. This one truly delivered - though I didn't peel the stems as well as I should have, as there were some really woody fibre bits throughout (oops), so I had to pick them out. But otherwise (if you are still reading this) it really was tasty - perfectly balanced flavours and texture (other than the stringy bits) - and the colour, wow - the addition of spinach took it to a new level. Oh, and I likely upped the cheese content, just a smidge.

2 tbsp unsalted butter
2 pounds broccoli, chopped into 1” pieces (include the stems but peel them and cut them into 1/4 inch-thick slices)
1 medium onion, chopped
2 garlic cloves, minced
1½ tsp dry mustard powder (or in my case, some Dijon – I never have dried mustard on hand!)
pinch cayenne
Salt
2-3 cups water
1/4 tsp baking soda
3 cups chicken broth
2 oz baby spinach
3 oz sharp cheddar, grated
1 ½ oz parmesan, grated
pepper to taste

In a large pot or dutch oven, heat butter over medium high heat. Add broccoli, onion, garlic, mustard, cayenne and 1 tsp salt. Stir frequently and cook until fragrant, about 6 minutes. Add 1 cup water and baking soda and bring to a simmer. Cook until broccoli is very soft, about 20 minutes.

Add broth and 2 cups water and increase heat to medium high. Bring to a simmer, then stir in spinach and cook until wilted, about 1 minute. Add cheeses and blend soup with an immersion blender (alternatively, you can transfer soup to a blender and blend in two batches).

Adjust consistency of soup to your liking with remaining water (I found it didn't need any more). Season to taste with salt and pepper.