Broccoli Cheddar Soup

Method

1. prep8 min
   Cut broccoli florets small — thumbnail size — and peel and dice the stems; the stems are sweeter than the tops and cook in the same time once peeled. Grate the cheddar off a block: bagged shreds are dusted with starch or cellulose to keep them loose, and that coating never fully dissolves, so it turns the finished soup grainy.
2. sweat8 min
   medium-low, no color
   butter + onion + celery + grated carrot + garlic, until the onion is translucent and slack. Keep it pale — browning here gives a sweet, caramel note that fights the cheddar.
3. mix2 min
   medium, stirring constantly
   + flour, cooked into the butter until it smells like toast rather than raw paste. Two minutes is enough to kill the floury taste and still leave the starch white; a darker roux thickens less, because the browning breaks the same starch chains you are relying on.
4. whisk4 min
   medium, adding liquid in stages
   + chicken stock a splash at a time, whisking smooth before each addition, then + milk + cream + bay leaf. Adding all the liquid at once leaves flour lumps that no amount of later stirring will dissolve, because each lump seals itself in gelatinized starch.
5. simmer12 min
   bare simmer, uncovered
   the base until it coats a spoon, then + broccoli + salt + pepper + dry mustard + nutmeg and simmer until the florets are tender at the stem. Stop there: broccoli held past about fifteen minutes releases its sulfur compounds and goes army-green, and that smell does not leave the pot. Fish out the bay leaf.
6. temper4 min
   off the heat, below 175°F / 80°C
   + cheddar in two handfuls, stirring each until it vanishes before the next. Off the heat is not optional — above roughly 175°F the casein network in cheddar contracts and squeezes out its fat, and the soup turns into stringy curds floating in greasy broth. The flour already in the base is what keeps the emulsion stable at all; there is no repair once it breaks.
7. season2 min
   Taste and correct salt last, since the cheddar brought its own and the uncovered simmer concentrated what was there. Smoked paprika, a dash of hot sauce, or worcestershire sharpen a soup that tastes flat but is already salty enough.