Preheat the oven to 325 degrees F.

Arrange 8 4-inch ramekins on a large rimmed baking sheet.

Cut the Key lime cheesecake into 8 even pieces and place in the center of each ramekin.

In a medium saucepan over medium heat, combine heavy cream, sugar, and salt.

Bring to a boil and stir until sugar dissolves.

While the cream is heating, whisk the egg yolks together. Add vanilla bean or vanilla extract and whisk.

Gradually add 1/4 cup of the hot cream mixture to the yolks, whisking constantly. Continue adding 1/4 hot cream mixture to the yolks until all combined.

Optional, strain the custard through a fine-mesh sieve into a clean bowl preferably with a spout. (Straining isn't necessary unless you think you may have cooked small portions of the egg yolks.)

Carefully pour or ladle the custard into the ramekins being careful to keep the Key lime cheesecake in the center of the ramekin.

Fill ramekin to the rim.

Place the baking sheet with the ramekins in it in the oven. Add water to the baking sheet until 1 about 1 inch deep.

Bake the creme brulee until the edges have set but the center still trembling when the ramekins are gently shaken about 20 to 25 minutes.

Remove the ramekins from oven and allow to cool on a wire rack until completely cooled.

Place in an airtight container or wrap individually and refrigerate for at least 2 hours or up to 3 days.

Remove the creme brulee from the refrigerator at least 30 minutes prior to browning the sugar on top.

To serve: Sprinkle the top of each custard with a thin even layer of sugar, about 1 tablespoon each. Use a kitchen blowtorch or oven broiler to melt and caramelize the sugar. You want the sugar to form a crispy top.

Allow the creme brulee to sit about 5 minutes before serving.