How to make a dessert with dynamically opening flower petals?
Gravity is making the petals open. If you look at the shape of the petals their center of gravity is towards the outside of the bowl, but they are being held in place by something underneath. I suspect that it's simply one piece of chocolate melted onto another. When the custard (warm or hot) is poured on it melts the bonds holding the petals in place allowing them to fall.