Heat oil in a saucepan over medium-high heat. Add onion and garlic. Cook, stirring for 3 minutes or until the onion has softened. Add sweet potato, and cook, stirring for 5 minutes. Add cauliflower cover and cook for 10 minutes, stir several times during this time.
Add stock, season with salt and pepper, cover and bring to a boil. Reduce heat to low and simmer for 25 minutes or until the potato and cauliflower have softened.
Blend until smooth. Return to a low heat and add cream. Cook stirring for 2-3 minutes or until heated through.