Passion fruit pulp strained and mixed with condensed milk, folded into whipped cream and set with gelatine. Four ingredients, no cooking, and it needs hours in the fridge before it can be turned out.
The gelatine is unflavoured, in every step. One instruction on this page had lost its prefix and asked for flavoured gelatine, which is a completely different product: sweetened, coloured and already set to a fixed strength. Fourteen grams of the plain kind is what sets this. Let the dissolved gelatine cool for a moment before it meets the cream. Poured in hot it can seize into threads on contact with the cold mixture, and those threads never disappear. Whip the cream only to soft peaks, because folding the passion fruit and condensed milk in thickens it further, and cream taken to stiff peaks first ends up grainy by the time everything is combined. It needs several hours in the fridge and the recipe does not say how many. Judge it by the mould: when the surface springs back under a finger and the mousse pulls slightly away from the sides, it is set. Ten passion fruit sounds like a lot and it is not, because most of a passion fruit is seed and shell.