Put milk, sugar and yeast in the bowl of a stand mixer.
Add the egg and vanilla extract.
Whisk everything for few seconds then place the hook attachment on the stand mixer.
Add flour gradually and mix until everything is well incorporated.
Add the softened butter and knead on medium speed for about 5 minutes or less until the dough is smooth. The dough is sticky at this point.
Cover the dough in the bowl with plastic wrap and kitchen towel.
Let rise until doubled in volume.
Sprinkle flour on a working board.
Dump the dough on the working board.
Deflate it and form small balls, the size of a tangerine.
Flatten the balls by hands into thin circles.
Cover with kitchen towel and let rise until doubled in volume.
Preheat vegetable oil in a pan.
Fry the beignets until golden brown on both sides.
Drain on a paper towel lined tray.
Roll the beignets immediately in granulated sugar.
Insert a knife into the side of each beignet and make a small incision.
Fill the beignets with Nutella, pastry cream, jelly, Dulce de Lethe, you name it! Use a piping bag fitted with a star or round tip.
Enjoy.