Mix everything except the butter. I used a Thermomix and knead for 2 minutes.
Add the butter and knead until window pane stage is reached, which is 4 more minutes on the Thermomix on knead mode.
Let it rise covered until double. For me, it took 1 hour.
Roll out dough evenly on a floured surface to 1 cm.
Cut with a doughnut cutter.
Place the doughnuts on a well floured surface, cover them and let them rise to 1.5 times this time, and not over.
Heat up the oil to 160C or 170C and fry one side, when one side is golden brown, flip over the other.
Drain the oil and place them on the kitchen towel to dry.
If doing the filled doughnuts, cut a small hole and then pipe in the jam or ganache.
Coat them with toppings when still hot.