– 2 tablespoons unsalted butter
– 1 small yellow onion finely chopped
– 1 1/4 teaspoons kosher salt
– ¼ teaspoon ground black pepper
– 3 carrots scrubbed and cut into 1/2 to 3/4-inch pieces
– 8 cups broccoli florets about 2 heads
– 3 cups cauliflower florets about 12 ounces or 1 small head
– 2 cloves garlic minced, about 2 teaspoons
– 4 cups low sodium chicken broth or vegetable broth
– 1/2 cup 2% milk whole milk, or half-and-half (the higher the fat, the richer the soup)
– 1 to 2 teaspoons Dijon mustard to taste (I use 2)
– ¼ teaspoon ground nutmeg
– Pinch cayenne pepper optional
– 4 ounces extra sharp cheddar cheese shredded (about 1 cup), plus additional for serving, do not use pre-shredded cheese, which does not melt as smoothly
– 1 tablespoon cornstarch
– 1/4 cup finely grated Parmesan or 3 tablespoons nutritional yeast