Take the all purpose flour,yeast in a bowl, add the milk, melted butter, sugar, salt and mix everything together.
Knead the dough well until it turns smooth and slightly sticky.
Lightly flour your working surface and knead the dough for few minutes. Punch the dough and roll the dough 1/2-inch thick with a floured rolling pin.
Cut dough using a round cookie cutter or else with a round glass.
Cover the donuts and let them sit to rise atleast for an hour.
Heat enough oil for frying, and fry the donuts both sides until they turns golden brown. Remove the excess of oil with paper towel.
For Pastry cream: Heat the milk in simmer, meanwhile whisk the egg yolks with sugar and vanila extract.
Add the hot milk slowly and whisk everything, transfer this mixture in a saucepan and whisk until they turns thick in simmer.
Pour it in a bowl and cover it with a clingfilm right on the surface of this pastry cream to prevent the skin forming and cool it completely.
Fill a piping bag with pastry cream.
For Chocolate Frosting: Melt the dark chocolate chunks with butter in microwave for 30 seconds.
Mix well and make a silky chocolate frosting.
For Assembling: Using a skewer or a sharp knife, make a hole on the side of the donut and then fill it with pastry cream.
Now dip the top of the cream filled donuts to the chocolate frosting.
Arrange on a wire rack and let it sit for a while until the frosting gets completely set.
Enjoy the donuts for your snacks or for your desserts.