Kosher salt and freshly ground black pepper, to taste
PREPARATION
Melt the butter in a Dutch oven or large pot over medium heat. Add onion and cook until starting to soften, about 4 minutes. Add garlic, and continue cooking for 1 minute more.
Stir in flour, then continue stirring until flour starts to smell toasty, about 2 minutes.
Whisk in stock, then whisk in half and half, and season with salt and pepper.
Stir in broccoli, cauliflower, carrot, and mustard and bring to a gentle simmer. Let simmer until vegetables are tender, about 15 minutes.
Remove from heat, then stir in cheese by the handful until melted. Adjust seasoning as needed and serve. Enjoy!