In large bowl, whisk egg and 2/3 cup sugar until smooth
In medium saucepan, bring the heavy cream to a simmer over med/high heat.
Add chopped white chocolate. Turn off the heat and whisk until the white chocolate is melted. add 1/3 cup of the white chocolate mixture to the egg yolk mixture whisking constantly to prevent the eggs from scrambling. add the remaining white chocolate mixture to the egg yolk mixture whisk until smooth. Add the Vanilla
Pour into eight 6 inch ramekins or custard cups. place the cups in a 9x13-inch baking pan add enough hot water so the cups sit in to 1-1 1/2 inches of water
Bake for about 45 minutes,( may take one hour depending on your oven. This recipe does not test like custard where you put a knife in and it comes out clean) until set. allow to cool then refrigerate the custards until chilled.
before serving, sprinkle the top of each with 1 teaspoon of sugar and place under the broiler for 3 minutes. re-chill in refrigerator for 5 minutes before serving
This can be easily halved if you want only 4 servings.
I skip the last step and do not put the sugar on and broil it.