Place whole, peeled carrots onto smoker rack. Smoke 1 1/2 to 2 hours.
Heat vegetable oil in a 5.5 to 7.5 litre soup pot over medium heat. Stir in onions, Scotch bonnet and garlic, cook until the onion has softened and turned translucent, about 5 minutes. Chop carrots and add to onions along with celery; continue cooking another 5 to 10 minutes until the celery softens.
Stir in turmeric and curry powder until evenly distributed; pour in vegetable stock. Bring to the boil over high heat, then reduce heat to medium-low and simmer for 1 1/2 hours, stirring occasionally.
Strain the vegetables out of the soup and puree in a liquidiser until smooth. Pour the puree back into the soup and continue simmering 30 minutes more.
Whisk butter into soup until melted, then stir in cream and season to taste with salt and pepper. Strain soup through a fine mesh strainer before serving.