Add two cups of water and trivet.
In a mixing bowl, add the egg yolks and sugar, whisk until the sugar is dissolved. Mix in the cream and vanilla and whisk just enough to get everything mixed together well (do not whip).
Pour the mixture into ramekins, cover tightly with foil and arrange in steamer basket so that all are sitting straight. Lower the basket into the pressure cooker carefully, and if you still have some vertical space and extra cups, you can stack the additional cups on top in a second layer.
Close and lock. Turn the heat to high and calculate 5 minutes cooking time for ramekins and 3 minutes cooking time for espresso cups at high pressure (8 and 5 minutes if you cook at low pressure).
Release pressure using the natural release method. Open the pressure cooker and carefully lift out the custards. Open the first and jiggle it. It should be nearly solid- they will solidify further when chilled. If they are still very liquid, pressure cook for an additional 5 minutes with the same opening procedure noted above.
Remove the custards and leave to cool uncovered for about 30-45 minutes.
Once the custards are cooled, cover them in plastic wrap and place them in the refrigerator to chill for 3-4 hours.
Before serving, sprinkle the top with a thin, even layer of raw sugar. Melt the sugar with a culinary torch or slide them under the broiler in your oven to melt and caramelize the sugar.