Source: Fine Cooking UPDATES: 1/23/2024: In an effort to achieve that shiny, crackly crust every time, I've made a few changes to the recipe, mostly to the method, which is reflected in the instructions below. I also now use 3 eggs as opposed to 4, 1 tablespoon vanilla as opposed to 1/2 teaspoon, and 1 teaspoon Diamond Crystal kosher salt as opposed to 1/2 teaspoon table salt.  Notes: A digital scale is best for measuring flour and cocoa powder. This one is reasonably priced. Buy it! Baking by weight will change you forever. There's no better time than right now.  Cocoa Powder: For years I used Hershey's natural cocoa powder. Recently, however, I switched to Droste Dutch Processed Cocoa, mostly because one of you told me there are concerning levels of lead in Hershey's cocoa powder. But now I've learned that Droste has even higher levels of lead than Hershey's. All of this said, if you do the math, each brownie likely contains roughly 4 grams of cocoa powder. Still not ideal, and I will report back if I find a cocoa powder that works well and has lower levels of lead. Stay tuned! In the meantime, here are some recommendations from readers: Stella Park's recommendation: Cacao Barry Extra Brute (2 pack) | (1 pack) Navitas Viva Naturals Organic Cocoa Fry's Rodelle The pan. For optimal results, Stella Parks recommends using an anodized aluminum pan, explaining that in an aluminum pan, “a well-whipped brownie batter will bake just fast enough, puffing beautifully along the way. The brownies will then settle as they cool, a transformation that creates their crinkly, flaky tops and fudgy middles.” She also recommends lining the pan with foil. One of you readers has also had success using this USA 8-inch metal pan.