Instructions

• Trim and prepare the leeks: cut off the root ends and the dark green tops, keeping only the white and light green parts. Slice each leek lengthwise, then cut crosswise into 1/4-inch-wide half-moons. Rinse the sliced leeks in a colander under cold running water, separating the layers to remove any grit; drain well.
• Heat 2 tablespoons olive oil in a large pot or Dutch oven over medium heat.
• Add the drained leeks to the pot and cook, stirring often, until they begin to soften, about 3 minutes.
• Add 3 minced garlic cloves to the pot and cook, stirring, until fragrant, about 1 minute.
• Meanwhile, prepare the cauliflower: rinse the head, cut it in half and then into quarters, slice out and discard the core, and chop the florets into about 1-inch pieces.
• Add the chopped cauliflower to the pot with the leeks and garlic and cook, stirring occasionally, about 2 minutes to lightly brown the cauliflower.
• Pour in 4 cups vegetable broth. Increase heat to bring the mixture to a boil, then reduce heat to low, cover, and simmer until the cauliflower is tender when pierced with a fork, about 15 minutes.
• Puree the soup until smooth: either use an immersion blender directly in the pot, or carefully transfer the hot soup in batches to a regular blender (do not fill the blender more than half full and hold the lid vent slightly or cover with a towel to allow steam to escape).
• Return any blended batches to the pot. Stir in 1/2 cup half and half (or milk) and gently reheat until warmed through (do not need to boil).
• Taste and season with salt and pepper to your preference.
• Serve the soup hot, garnished with fresh thyme and/or grated cheddar cheese if desired.