Sunchoke and Cauliflower Soup

Name: Sunchoke and Cauliflower Soup
Ingredients: 2 tablespoons unsalted butter, plus 2 teaspoons softened butter; 1 small celery rib, minced; 1/2 small onion, minced; 2 cups chicken stock or low-sodium broth; 3/4 cup whole milk; 1 pound cauliflower, cut into 1-inch florets; 6 ounces sunchokes, peeled and cut into 1-inch pieces; 1 thyme sprig; 1 small garlic clove, minced; Salt; Four 1/4-inch-thick baguette slices, cut on the bias; 1 tablespoon freshly grated Parmigiano-Reggiano cheese; Freshly ground pepper; 1/2 cup sunflower sprouts