Preheat the oven to 300 degrees F.

In a medium saucepan, heat the heavy cream on medium heat until just steaming, then add the white chocolate and stir well until the white chocolate dissolves.

In a medium bowl, whisk together the egg yolks, sugar, and salt together until light in color. Slowly pour ½ cup of the heated cream into the yolks, stirring the yolks constantly. Once full incorporated, slowly drizzle the remaining cream into the yolks, again while still constantly stirring the yolks.

Place a heaping teaspoon of blackberry jam into the bottom of your ramekins and place the ramekins into a 9x13 baking pan. Slowly pour the cream mixture into the ramekins. It is best to go slowly as possible and more toward the side of the ramekin to prevent the jam from swirling in the cream. If you are not concerned about how it looks, no need to be as careful! Pull out the oven rack a bit so you can place the baking pan in the oven, do not close the door.

Very carefully pour water into the baking pan, being very careful as to not get any drops of water into the ramekins. You want enough water to cover the bottom of the baking pan, but not enough for it to reach the top of the ramekins. Push the oven rack back in carefully and close the oven door. Bake for about 45 minutes, or until the sides are set, but the middles are still a little jiggly. Remove from the baking pan and chill completely - about 3 - 4 hours in the refrigerator.

Mix the sugar and salt together for the topping and sprinkle evenly among the ramekins. Caramelize with a kitchen torch, or the broiler in your oven.