In a bowl, whisk the warm milk with sugar and instant yeast until combined.
Whisk in the egg and salt until smooth.
Add the flour and mix until a shaggy dough forms.
Knead the dough until it starts to smooth out, then knead in the room-temperature butter until fully incorporated and the dough is soft and elastic.
Cover and let rise until doubled in size (about 60–90 minutes).
Roll dough to about 1/2-inch thickness and cut donut shapes.
Let cut donuts rise until puffy (about 20–30 minutes).
Fry in hot oil until golden on both sides
Drain briefly, then coat as desired
