Place the cold water in a small bowl and sprinkle gelatin over; let stand until it sets, about 10 minutes. Do not stir.

Meanwhile, combine cream, sugar, and salt in a small saucepan over medium heat. Bring the mixture to a simmer, then add the gelatin and whisk until dissolved. Remove from the heat and pass through a fine mesh sieve to remove any lumps. Set aside to cool down slightly, about 30 minutes.

Whisk in buttermilk followed by the crème fraîche. Divide the mixture among eight 6-ounce jars, ramekins, or glasses. Cover and refrigerate until set, at least 5 hours but up to 2 days.

When ready to serve, top each pot with a generous tablespoon of jam before enjoying.