Preheat oven to 325ºF (160°C)
Combine egg yolks and sugar together in a bowl, whisking until the mixture becomes thick and pale yellow. Add the vanilla and approximately ¼ cup of the heavy cream, whisking until incorporated and smooth. In a small pot, heat remaining heavy cream to a simmer. Remove from heat.
Slowly drizzle hot cream mixture into the egg mixture, whisking constantly.
Pour into 4-6 ramekins or custard cups, and arrange in a large pan.
Carefully add water to the large pan, till about halfway up the sides of the ramekins.
Bake until custard is set, but wiggles in the middle – about 45-50 minutes.
Remove from oven, allow to cool to room temperature, and then chill for at least 2 hours.
When ready to serve, sprinkle 2-3 teaspoon sugar evenly over each custard. Use a small, hand held kitchen torch to melt sugar.