Donuts filled recipe

In a bowl, pour the milk and add the baker’s yeast with a teaspoon of sugar.
Mix and let stand for 10 minutes.
In the bowl of the stand mixer, pour the flour,
the lightly beaten egg, the melted butter, the sugar and the mixture of milk and yeast.
Beat the dough vigorously for 20 minutes,
until it becomes soft and elastic
By hand: In a bowl, combine the butter, egg,
sugar and a pinch of salt.
Add milk with baking powder and flour.
Mix well and transfer everything to a lightly floured work surface.
Keep kneading with your hands until you get a smooth, elastic dough.
Put the dough in a bowl covered with a cloth and let rise until it has doubled in volume.
My advice is to leave it in a turned off oven with the light on.
After the rising time, roll out the dough into a rectangle
half a centimeter thick on a lightly floured work surface.
Using a cookie cutter, cut out 6cm discs.