Break the chocolate into pieces and melt in the microwave for about 3 minutes, or in a bowl over a pan of simmering water. Don’t expect white chocolate ever to melt quite into the molten smoothness of dark: once it’s lost its shape, it’s melted enough; any more and it will start to seize. Set the bowl aside, and let the chocolate cool a little.
Beat the egg whites until stiff but not dry. Mix the egg yolks into the cooled chocolate, though be gentle to ensure it doesn’t seize. Cut the passionfruit in half and scoop them, juice, pulp, seeds, into the yolk and chocolate mixture, then fold into the egg whites until completely incorporated.
Line the bottom of either a big glass bowl or eight to ten small glasses with a layer of raspberries – it’s hard to be specific: it depends on the diameter of the glasses, or bowl, at the base really – and pour over the mousse. Leave for a couple of hours to set in the fridge, or for at least 4 if you’re using one large bowl. Strangely, given that I lean normally towards the communal rather than individual serving, I generally go the one-glass-one-person route. I think it’s because this is intense enough to require – even for me – small portions, and it’s impossible to dollop out as little as would fill a small glass without seeming mean.