Combine flour, salt, sugar, yeast, milk, and eggs in a mixer for 10 minutes until elastic.
Mix in softened butter for 5 minutes until the dough is smooth and glossy.
Cover dough and chill in the fridge for at least seven hours or overnight.
Knead the chilled dough briefly on a lightly floured surface.
Divide into 18 portions, fill with chocolate or raspberries, shape into balls, and prove for 20 minutes.
Heat sunflower oil in a deep-fat fryer to 170°C.
Fry chocolate doughnuts for 3 minutes per side until golden and drain on kitchen paper.
Fry raspberry doughnuts similarly and roll immediately in caster sugar while hot.
Pipe melted dark and white chocolate in a zigzag pattern over the chocolate doughnuts.