Bloom the gelatin in cold water for 10 minutes, drain and screen out the excess. Bring the cream, milk and sugar to a boil over medium heat, remove from the stove and whisk in the gelatin until fully dissolved. Strain the mixture through a fine mesh sieve into a clean bowl and whisk in the grappa. Pour the panna cotta mixture into 6 ramekins and place in the refrigerator to set (overnight is best). Drizzle with the good olive oil and sprinkle a few flakes of Maldon on each one before serving.