Lactose free double cream, for drizzling - optional
Melt the lactose free butter gently in a medium saucepan then add the carrots. Cover with a lid and leave over a low heat, stirring occasionally, until the vegetables have softened but not coloured (about 12 minutes).
Pour in the stock and sprinkle in a little salt.. Bring to the boil and simmer, partially covered, for 20-30 minutes or until the vegetables are very soft. Take off the heat and leave to cool for a few minutes.
Strain the vegetables through a sieve set over a bowl. Reserve the liquid. Transfer the vegetables to a food processor or blender.
Process until smooth, adding enough of the strained liquid to make the mixture turn easily in the machine. Set the sieve over the cleaned pan and push the puréed vegetables through (this step is not essential but gives the soup a very smooth finish). Pour in the liquid and stir well to blend.
Tip in the orange juice and mint and gently reheat the soup. Stir and taste to see if more salt is needed, then pour into warmed bowls. If you like the idea of the lactose free cream, drizzle a little over the top.