- 3 tablespoons unsalted butter
- 1 medium yellow onion, diced small
- 1 medium head cauliflower, trimmed and cut into 1 1/2-inch pieces
- 4 cups low-sodium chicken broth, plus more if desired
- 5 1/2 ounces sharp white cheddar, grated (1 1/2 cups)
- Coarse salt and ground pepper
- 1/8 teaspoon cayenne pepper
- In a large pot, melt butter over medium. Add onion and cook, stirring occasionally, until softened, 8 minutes. Add cauliflower and cook until just beginning to brown, 12 minutes. Add broth and 1 cup water; bring to a boil over high. Reduce heat and simmer until cauliflower is very tender, 20 minutes. Transfer mixture to a large bowl.
- In batches, fill a blender halfway with mixture and puree until smooth (use caution when blending hot liquids). Return pureed soup to pot and add more broth or water for a thinner consistency, if desired. Heat over medium until warmed through; add cheese and stir until melted. Season with salt and pepper. Serve sprinkled with cayenne.
To store, let soup cool completely, then refrigerate in an airtight container, up to 2 days.