Chop the onions and put them into a saucepan with the rice. Cover generously with cold water; add salt and pepper plus a good pinch of nutmeg. Cover and place over a medium heat until boiling.
Reduce the heat to a low simmer for about 20 mins until the onions and rice are soft.
Blend and return to the pan but not to the heat. Cut the butter into small pieces and beat it in. Now add the cream little by little and adjust the seasoning. Reheat gently over a very low heat do not allow to boil.