Preheat the oven to 180C / Fan 160C / Gas mark 4. Roast the sweet potatoes whole for 1 hour or until cooked through.
Place the unpeeled garlic cloves on a double layer of kitchen foil. Drizzle with a little olive oil, then seal the foil around them. Roast for 30-35 minutes or until the cloves are soft and squishy.
Once the sweet potatoes are cooked, allow them to cool slightly - just enough to allow you to handle them - and scoop out the flesh into a saucepan on a low heat.
Peel the roasted garlic cloves and mash them into the sweet potatoes along with the cinnamon and some salt and pepper to taste. Cook the purée for a further 6-8 minutes, stirring to prevent the mixture from sticking.
Finish with the butter, stirring well to incorporate it and make the purée smooth. Serve with a little drizzle of pomegranate molasses.