In a saucepan, over medium heat bring 2 cups of water to a simmer.
In a heatproof bowl, whisk egg, egg yolks, sugar until well combined. Add the passionfruit pulp and whisk until smooth.
Place the bowl on top of the saucepan of simmering water and stir egg mix until it thickens and reaches 70C. Use a kitchen thermometer to test.
When it reaches a custard-like consistency, turn off heat and stir in butter a little at a time. Let it cool to thicken further before spooning over pavlova, top with whipped cream, fresh berries and passionfruit.