Cream the butter and sugars together in a large mixing bowl or the bowl of a stand mixer.
Add the egg and vanilla extract.
Add the flour and salt. Mix well.
Form the dough into a disc shape, wrap it with plastic wrap, and chill for 30-60 minutes.
Roll the dough about 1/4" thick. Cut out an even amount of back cookies and cookies with a hole in the center for the front of the sandwich. Chill 10 minutes before baking to help keep the shape and stop the cookies from spreading too much.
Bake at 350℉ (175℃) for 10-12 minutes.
Let cool.
Spread Nutella on bottom cookies.
Dust sugar on top of the cookies with the cut out in them, and sandwich the two together.