Preheat oven to 300°.
Prepare a 2.5 quart roasting pan or baking dish with 8 custard pots, oven-safe glass jars, or ramekins. Have a kettle of water ready by your oven.
Place cream and vanilla in a medium saucepan. Bring to a boil over medium heat. Remove from heat and set aside.
Whisk egg yolks, salt, and 2 Tbsp. sugar in a large bowl, set aside.
Combine remaining sugar and 1/2 cup water in a heavy gauge metal pot, at least 3 quarts in size. Stir. You are stirring until the sugar is largely dissolved. The water will begin murky and end somewhat opaque. This could take up to 5 minutes of constant stirring.
Set the pot on top of the stove. Make sure there are no sugar granules on the side of the pot. Use a damp pastry brush to brush down the sides of the pot to get all of the sugar crystals into the mixture.
Turn the burner on to medium heat. Stir some at the beginning to make sure that all of the sugar is dissolving. Once the sugar is dissolved and the mixture is beginning to bubble, stop stirring. RESIST THE DESIRE TO STIR.
Let the sugar and water cook together and work their science. The sugary mixture will graduate through the various sugar stages as the water evaporates and will eventually begin to caramelize. DO NOT REDUCE OR INCREASE THE HEAT. AGAIN RESIST THE DESIRE TO STIR. You can gently swirl the pan to achieve even caramelization if it looks to be necessary.
Watch the pan closely as the process moves quickly. Remove the pan from the heat as soon as your caramelized sugar has reached its desired color. The darker you can get the caramel without burning it the better the end product will be, but use caution and use your nose to smell for "sweet" versus "burn."
Slowly add warmed cream to caramel (mixture will bubble and steam vigorously), stirring constantly until very smooth.
With a 1/4 measure cup of the caramel mixture, dribble slowly into the egg mixture while whisking constantly with your other hand to 'temper' the eggs. Whisk in the remainder of the caramel mixture into the eggs SLOWLY until all the caramel has been incorporated.
Move the assembly close to your oven. Divide custard among jars or ramekins and replace into the roasting pan. Using the kettle, fill the roasting pan with water to come halfway up sides of ramekins. CAREFULLY LIFT THE ROASTING PAN INTO THE HEATED OVEN.
Bake until custard is just set but still jiggly in the center, about 55 to 65 minutes. CAREFULLY remove ramekins from roasting pan and place on a wire rack to cool for 30 minutes. Chill custards, uncovered, at least 3 hours. Sprinkle with flaky sea salt to serve.