In a small bowl, mix ½ cup orange juice with gelatin powder, stirring to ensure no lumps. Leave to stand. Heat remaining 1 cup orange juice in a small pot with honey and sugar, stirring to dissolve. Allow to boil then remove from heat and mix in lemon juice and soaked gelatin mixture, stirring until gelatin is fully dissolved.
Place egg whites in the bowl of an electric mixer and whisk to soft-peak stage. With the imxer still running, slowly add the hot citrus mixture. As soon as it is incorporated, turn off mixer and leave for 15 minutes to allow mixture to cool and begin to set, then beat until thick and fluffy – this will take about 15 minutes (it will take a while before it starts to thicken; be patient). When ready the mixture will be very thick (like stiff whipped cream) and hold its shape. Transfer mixture to a large bowl.
In the uncleaned mixer bowl add cream, zests, vanilla, cardamom and Grand Marnier. Whisk until cream just gets to firm peak stage, but don’t overwhip or it will split with the extra folding. Gently fold a little of the whipped cream into the egg-white mixture and, once incorporated, gradually fold in the remainder.
Half-fill 8-10 serving glasses with the soufflé mixture. Spoon over a tablespoon of passionfruit pulp before topping with remaining soufflé mixture. Chill until ready to serve, then garnish with Hazelnut Orange Sugar.
For Hazelnut Orange Sugar: Process roasted hazelnuts, sugar, zest and cardamom powder until you get a reasonably fine rubble. Keeps for weeks in a sealed jar.
Souffles can be made a day ahead and refrigerated.