Special equipment: four 5-ounce ramekins
Sprinkle the gelatin over the water in a small bowl and let soften for at least 5 minutes. Lightly oil four 5-ounce ramekins with baking spray or flavorless oil. Set aside.
Bring the cream and honey to a light simmer in a small saucepan, and then turn off the heat. Whisk to incorporate all the honey evenly, then pour into a mixing bowl. Whisk in the gelatin. Whisk for at least a minute to make sure it is very evenly distributed and that no lumps remain. Whisk in the milk. Pour into the ramekins and put in the fridge to set. The panna cotta will need at least 2 hours to set, preferably 4.
Top each with pistachios and sea salt to taste.