8 ounces – uncooked elbow macaroni
1 ½ – tablespoons unsalted butter
1 ½ – tablespoons flour
¾ cup – low-sodium chicken or vegetable broth
1 ¼ cups – reduced fat milk
¾ teaspoon – dry mustard
¼ teaspoon – kosher salt
12 ounces (about 4-5 cups) – cauliflower florets cut into 1” chunks (from 1 small head)
1 ½ – cups shredded cheese (cheddar, Gruyere, Monterey Jack, etc.)
Optional toppings: Fresh parsley, freshly ground pepper
Cook the pasta according to package directions. Drain and set aside.
Melt butter in a large saucepan over medium-low heat. Add flour and stir constantly just until roux puffs slightly, about 1-2 minutes. Stir in the broth, milk, dry mustard and salt until smooth.
Increase heat to medium-high. Add cauliflower and bring milk-broth to a rapid simmer, stirring frequently. Immediately reduce the heat back to medium-low, cover and simmer until cauliflower is very tender, about 10-12 minutes, stirring occasionally.
Carefully transfer cauliflower and milk-broth to a blender. Firmly hold the lid to prevent hot liquid from escaping and puree until completely smooth, about 20-30 seconds. Return puree to pan over medium-low heat. Add the shredded cheese and cooked macaroni, stirring well until cheese has melted. Serve immediately with fresh parsley and additional salt and pepper to taste, if desired.