- Preheat the oven to 180ºC/gas 4. Place the sweet potatoes in a large pan, cover with water and cook for 20–25 minutes, until tender. Drain and mash well, cool a little then stir through the butter, sugar, rum (or lemon juice), and lime zest and juice.
- In a separate dish, beat together the remaining ingredients, and stir into the sweet potato mixture.
- Grease and line a 900g (18cm x 8cm deep) loaf tin. Turn mixture into the tin and bake for approx 1½–1¾ hours until firm.
- Check the firmness by inserting a skewer – it should come out clean when the dish is cooked.
- You could also put the mixture into individual ramekins/dishes and bake for around 45 mins.
- Keeps in the fridge for up to 5 days. Warm up a slice and serve with reduced-fat crème fraiche or yogurt.
- If you don't want to use rum, use 3 tbsp lemon juice instead.