Using an immersion blender, mix the Yumgo Yolk powder, water, oil and sugar.
Once the liquids are boiling, pour in the Yumgo mixture and bring to the boil for 1 minute.
Pour over the chocolate and emulsify with an immersion blender without incorporating any air.
Remove and chill for 24 hours.
The next day, shape the ganache into balls, insert a caramelised hazelnut in the centre and place in the freezer for a few minutes until the chocolate hardens.
Cover the truffles with a thin layer of melted chocolate and immediately place in the cocoa powder.