1. In a medium saucepan, whisk together the dry milk powder, flour, salt, thyme, and cayenne.
2. Gradually
whisk in the liquid milk until no lumps remain. Cook, stirring
constantly, over medium heat until the sauce is slightly thickened,
about 5 minutes.
3. Stir in the bell pepper and cook until crisp-tender, about 2 minutes.
4. Stir in the Cheddar and Parmesan, and cook until the cheeses have melted, about 1 minute.
5. Remove from the heat and stir in the scallions and mustard.
6. Meanwhile, in a vegetable steamer, steam the cauliflower until tender, about 4 minutes. Transfer to a medium bowl.
7. Add the cheese sauce, tossing until the cauliflower florets are well coated.
Makes 4 servings