Pre-heat oven to 300°F (150°C)
Beat egg yolk, 4 tbsp white sugar and vanilla extract in a mixing bowl until thick and creamy.
Pour cream into a saucepan and stir over low heat until it almost comes to boil.
Remove the cream immediately and pour into egg yolk mixture while stirring continously add espresso shot.
In a double boiler, heat the mixture until mixture lightly coats the back of the spoon. Remove the mixture from heat and transfer into prepared ramekins.
Baine marie ramekins and bake for 30 minutes. Remove from oven and cool to room temperature.
Refrigerate for at least 1 hour or overnight.
Remove from refrigerator, sprinkle some sugar on top and torch it until sugar caramelizes. Serve immediately.