Preheat the oven to 160°C/325°F/Gas 3. Mix the eggs, lemon zest and caster sugar for one minute. Gently mix in the cream, then the lemon juice and finally the desiccated coconut. Pour into the pastry shell and bake until golden all over (about 40 minutes). Remove and cool – leave for 1 hour to firm up.
To make the accompaniment, let the mascarpone warm to room temperature before putting it into a bowl with the double cream and sugar. Whip until it begins to thicken, add the passionfruit pulp and beat until firm.