2 tablespoons butter 3 leeks (white and light green parts only), sliced 1 tablespoon fresh thyme leaves, plus more for serving salt and black pepper 1 bunch broccoli, cut into florets (about 6 cups) 2 cups low-sodium vegetable broth

Heat oven to 400° F. Heat 1 tablespoon of the butter in a large pot over medium-high heat. Add the leeks, thyme, and ½ teaspoon each salt and pepper. Cook, stirring often, until very tender, 10 to 12 minutes. Add the broccoli, broth, and 2 cups water and bring to a boil. Reduce heat and simmer until the broccoli is crisp-tender, 6 to 8 minutes. Working in batches, transfer the mixture to a blender and puree until smooth.

Reheat the soup if needed and serve sprinkled with thyme leaves.