Preheat oven to 400°. Mix chickpeas with oil and spices and roast in oven for about 30 minutes, until golden and crispy, stirring halfway.Meanwhile, heat oil in large saucepan on medium. Add celery, carrots, onion, and garlic, and cook 10 minutes.Lower heat to a simmer and add tomatoes, broth, chickpeas, and butter and let simmer for about 20 minutes.Add coconut milk. Puree until smooth with an immersion blender (or CAREFULLY in a regular blender with a little venting or it will explode all over you). Plate and garnish with roasted chickpeas and fresh or dried basil.