Regular sugar is a bunch of tiny, sharp crystals. Powdered sugar is those same crystals, blitzed into a fine dust. Manufacturers add a little cornstarch to stop it from clumping.
That cornstarch is the party pooper. It changes everything about texture and taste. You’re not just swapping sugar; you’re adding secret thickener.
Baking? Proceed With Caution
If you’re making a cake or cookies, do not do a 1:1 swap. Your cookies will spread like flat pancakes. Your cake might turn into a dense, gummy brick.
Why? Powdered sugar has less sweetening power by volume. You need more of it to get the same sweetness. Plus, the cornstarch absorbs moisture, messing with the chemistry.
But here’s the quirk: Some shortbread recipes love powdered sugar. It makes them melt-in-your-mouth tender. It’s the secret to that “sand cookie” texture.
