These are less work than cookies and just as delicious!
In a stand mixer, beat butter and shortening together until combined (about a minute). Add sugars and beat another minute or two. Add vanilla and egg. Beat again (I know, so much beating here. . . ).
Add the flour, soda, and salt. Mix JUST until combined. It will look over-floured for a few seconds, but should come together fairly quickly.
(adpated from The Bite-Sized Baker)