No seriously. " from Jestei. Do you sift the powdered sugar?

I always sift two things: powdered sugar and cocoa powder. These two ingredients are particularly prone to clumping, so I find it better to play it safe and spend an extra 2 minutes (if that) sifting. No one wants big clumps of sugar in their dessert.

you don't have to but if you do sift dry ingreds for cookies and cakes, the product comes out more tender/lighter. I started doing it awhile ago for this reason.

No you should be fine just following the directions as shown