Using an electric beater, whisk up the egg yolks and castor sugar.
Bring the heavy cream, vanilla extract, cinnamon sticks and nutmeg up to a warm heat in a pot (DO NOT BOIL).
Temper the egg yolks and sugar by pouring a small amount of the warm cream mixture into the large mixing bowl. Mix well. Then, pour and the remaining cream mixture into the eggs.
Pour the cream mixture into 6 ramekins until about 3/4 full. Remove any air bubbles on the surface with a spoon. Wrap the ramekins tightly with foil.
Add 1 cup of water and steamer rack in your Instant Pot. Place the wrapped ramekins on steamer rack (4 at the bottom with 2 stacked on top).
Pressure Cook at Low Pressure for 13 minutes, and 15 minutes Natural Release.Then, release remaining pressure. IF you choose to go for a thicker brulee then Pressure Cook on HIGH for 7 minutes, with a NP release of 5 minutes.
Unwrap and refrigerate your brulee for a minimum of 4 hours, preferably overnight.
Before serving, sprinkle the remaining castor sugar over the top and use your blow torch to achieve that beautiful hard, crackled caramel top!