Speaking as nothing resembling a mother,

[Jasper]

Why do people even use granulated sugar in cookies when powdered is so far superior?

[Sir Squid Diddimus]

because for some cookie recipes you cannot properly cream the eggs and sugar together w/ powdered sugar because the granules are too fine.
the sugar crystals break the fats and proteins apart in the eggs for a different kind of batter, say, chocolate chip batter or sugar cookie batter.
many cake recipes call for the same technique.

if you use powdered sugar the batter will not be the right consistency and may result in super crispy cookies or flat cakes.

also powdered sugar tends to seem sweeter than granulated because of it's super fine texture, thus you would need to use less, but how much exactly? and will it throw off your dry to wet ratio? probably.

however 10x powdered sugar is teh best for frosting.

[Jasper]

But for general cookie batter purposes, it seems to produce much more ideal cookies.  Chewy inside, slight outside crunch.

[Bruno]

This discovery could very well be the thing we need to finally bring down the evil cookie cartels.

[Nast]

What is everyone's opinion of superfine sugar?

[Jasper]

Every size of sugar crystal has a use, but for mixing I'm of a mind to try out some superfine sugar mixes.

[Nast]

I don't think one has to buy it from the store, because to make superfine sugar, you can just whirl some normal granulated sugar in a food processor until it's powdery.

I was wondering what it would be like in cookies, because it's sort of a middle ground between powdered sugar and the kind used in normally used in baking.

[Sir Squid Diddimus]

GRANULATED SUGAR IN COOKIE BATTER!
                        /

[Nast]

OH GOD IT HAS TEETHS

[Jasper]

GRANULATED SUGAR IN COOKIE BATTER!
                        /

Why so Simian?

[Mesozoic Mister Nigel]

Powdered sugar contains corn starch, which can throw off some cookie recipes.

For proper cookie making, you are supposed to cream the butter and sugar until they are "light", which is a euphemism for beating them until the sugar crystals actually dissolve in the butter. It's a laborious process but yields superior results. It's easier if you use confectioner's sugar, which is finer than powdered but contains no corn starch.

[Sir Squid Diddimus]

Alton Brown has an entire episode on why you cream the eggs and sugar together.
The sugar crystals themselves play a big role in the final outcome.

[Triple Zero]

problem with powdered sugar is that it's often not just sugar but has a lot of chemicals to make it stay powdery added. i've seen as low as 66% actual sugar content.

so if you do this, use the food processor.

or how about using the medium-small-size cooking sugar that's meant to be used in cookies? [which is called bastard-sugar in Dutch, for some reason unknown to me] [maybe this is what Nigel means with confectioner's sugar]

what is Alton Brown?

[LMNO]

google "good eats"

It's like food-nerd porn.

[Jasper]

Confectioner's sugar.  Interesting.