hello, this recipe looks great. Should I use unsweetened or sweetened cocoa powder?

sumati, in the u.s., 'cocoa powder' for baking, is always unsweetened. (It can differ between 'dutch process' and regular, but that is a whole other topic) We call the sweetened powder 'cocoa mix' usually and it is typically used to make chocolate milk or fudge sauce.

Unsweetened is always the default in baking, unless otherwise specified.

And it is a great cake!

Unsweetened!