Melt two tablespoons of ghee in large stock pot with a cover. Add onions and cook until translucent.
Cut cauliflower into 4 quarters. Add ¾ of the cauliflower to the pot, reserve ¼ of the cauliflower for later.
Add the chicken broth, water, salt, and remaining ghee. Bring to a boil, reduce to medium heat, cover, and cook for 10 minutes.
Break apart the remaining cauliflower into small florets.
Remove the pot from the heat, carefully place entire mixture into a large blender. Blend until completely smooth, taking care to use the hot liquid vent with a kitchen towel/cloth.
Pour the blended mixture back into the pot.
Stir in the cauliflower florets, clams, and add 1 sprig of rosemary.
Bring pot to a simmer and cook for an additional 10 minutes.
Remove rosemary sprig prior to serving.
Add salt and pepper to taste. Optional: garnish with crumbled bacon and dried rosemary.