Lightly grease the ramekins with a touch of the butter.
Dissolve the gelatine in the milk.
Place the cream, sugar and essence in a saucepan and bring just to the boil then reduce to a simmer for 5 minutes.
Remove the saucepan from the heat and let stand for 5 minutes.
Add the milk and gelatine to the cream and mix well (be sure to get any gelatine that may have settled and not dissolved).
Let stand a further 10 minutes.
Stir and strain through a fine sieve and pour into the ramekins and allow to set in the fridge for approx 4 hrs.
Note: I like to remove my panna cottas from the fridge about an hour before serving. I find this allows the flavours to marry without the distraction of excess chill. If you plan to do the same, make sure they stay stiff enough to serve. This is another good excuse to eat one of those extra panna cottas prior to dinner, “quality control.”