Preparation

1. Place six 5-ounce ramekins in the baking pan and set them near the stove where the sugar is being cooked.
2. Put ¾ cup of the sugar and the salt into a medium, heavy-bottomed saucepan. Add enough water to cover the sugar so that the mixture resembles wet sand (you may not need all of the water). Set over medium and cook, without stirring, until sugar has dissolved and mixture turns a light amber color. Working carefully and quickly so the caramel does not harden, pick up a ramekin and add a small amount caramel and swirl to fully coat the bottom. Repeat with the remaining ramekins.*
3. Return the pan to the stove, with the heat reduced to low. Very carefully whisk in the butter, then whisk in the milk, cream and vanilla – this will steam and bubble a bit, so whisk off the heat if you prefer. Increase the heat to medium and bring mixture to just a simmer.
4. While the milk/cream mixture is heating, whisk the eggs, yolks and remaining ¼ cup of sugar together in a medium mixing bowl until lightened; reserve.
5. Once the milk/cream mixture has come to a simmer, whisk about one-third of the hot mixture into the egg/sugar mixture. Whisk in another third of the hot liquid, then return the combined mixture to the saucepan. Reduce the heat to low and using a wooden spoon, stir the mixture constantly, in a figure-eight pattern, until it thickens slightly and coats the back of the spoon. This mixture must NOT boil or the eggs will overcook – the process should only take a few minutes.
6. Pour the mixture through a fine mesh strainer. Evenly divide the strained mixture among the six ramekins, pouring on top of the set caramel.
7. Adjust the rack to position 1 and select Bake at 275°F for 30 minutes. Once the oven beeps to signal that it is preheated, put pan of filled ramekins into the oven and fill pan with water. Allow custards to bake until just set – they should still be jiggly when you tap the ramekin. Remove from oven and using tongs or a dish towel, carefully remove ramekins from the tray to prevent continued cooking.
8. The custards can be served warm or cold. If serving immediately, lower each ramekin into cold water for a few minutes. Using a knife or offset spatula, scrape around the inside walls of the ramekins to loosen the custard. Invert a serving plate on top of the ramekin and then quickly and carefully flip over and tap a few times to remove. The caramel will pool around the custard and create a sauce; sprinkle top with a pinch of fleur de sel. This serving style is called a Crème Caramel Reversée and it is spectacular in presentation. If serving at a later time, cool and cover each tightly with plastic wrap and refrigerate until using. The custards can be stored in the refrigerator for up to 5 days.

*If pouring the caramel into the ramekins is something that you are not comfortable doing, skip this step and immediately move on to step 3. It will still be delicious and the caramel flavor will come through beautifully, but you will not have the sauce at the bottom of the custard. Because of that, you do you not have to invert the custard; you can serve in the ramekins and sprinkle the top with the fleur de sel.