Step 1

In a large pot over medium-high, melt 4 tablespoons of butter and cook, stirring often, until browned, 2 to 3 minutes. Add the harissa and cook, stirring, until fragrant, about 30 seconds, then transfer to a small bowl; set aside. In the same pot over medium, melt the remaining 2 tablespoons butter. Add the onion and ½ teaspoon salt, then cover and cook, stirring occasionally, until softened but not browned, 6 to 8 minutes. Add the cauliflower, broth and 3½ cups water. Bring to a simmer, cover and cook until the cauliflower is fully tender, 15 to 20 minutes. Cool uncovered for about 5 minutes.

Step 2

Using a blender and working in 2 or 3 batches to avoid overfilling the jar, puree the mixture until smooth. Return the soup to the pot and reheat over medium, stirring, adding water as needed to thin. Taste and season with salt and pepper. Serve drizzled with the harissa butter, sprinkled with dill and with pita chips on the side.