Preheat the oven to 160℃. Heat the heavy cream until boiling.
In a mixing bowl/jug add the egg yolks, sugar and vanilla. Whisk well.
Steadily pour in the hot cream and whisk constantly - do not stop whisking as we are tempering the eggs by adding the cream slowly. Add the espresso and whisk.
Pour into two glasses. Place the glasses in a deep baking tray, fill the tray with hot water, half the way. Place in the oven on the middle rack for 35-40 mins until the sides are set and the center is a little jiggly.
Once baked, transfer the fridge to set, anywhere between 4-12 hours. When ready serve, sprinkle over the additional castor sugar and brûlée the top. Serve immediately with some biscotti.
Notes
Make sure to whisk the hot cream into the egg mixture slowly. To avoid the eggs from scrambling.
Let the Crème Brûlée set in the fridge for 4-12 hours before serving.