- Combine the sugar, eggs and starch, and grind with a whisk until smooth.
- Bring the milk to a boil (no need to boil), and pour it in a thin stream into the egg-sugar mixture, stirring constantly. After that, the whole mass must be mixed until the sugar is completely dissolved, and only then put the bowl with it on a low heat.
- Bring the mass to a thickening, heating it over a low heat, stirring.
- Remove the mass from the heat, add the soft butter, and mix until smooth.
- Cover the custard base with cling film "in contact", and let it cool.
- Whip the ingredients for the pistachio base until smooth and fluffy.
- Mash the cooled custard base with a blender, and combine it with the pistachio base using a mixer.