Step 1

Preheat oven to 325 degrees F. Put a full kettle of water on to boil.

Step 2

Whisk egg yolks, sugar, vanilla extract and salt in a medium bowl.

Step 3

Split vanilla beans down the middle, then use the tip of a sharp knife to scrape all the black paste from them into a medium saucepan. Add the bean pods and milk to the pan. Bring to a gentle simmer over medium heat. Slowly whisk into the egg mixture. Place a fine sieve over a large bowl and strain the custard into the bowl (discard the pods).

Step 4

Place eight 6-ounce ovenproof baking dishes (or ramekins) in a large roasting pan that's at least 2 inches deep and fill with the custard. Pour the boiling water around the baking dishes until it comes about halfway up the sides. Cover the pan loosely with foil.

Step 5

Bake the custards until set around the sides but still a bit wobbly in the center, 30 to 35 minutes. Using oven mitts, transfer the baking dishes to a wire rack and let cool to room temperature. Cover and refrigerate until cold, at least 3 hours and up to 3 days.