I buy organic eggs, French butter, Marcona almonds. And yet, without giving it a second thought, I've always used Hershey's cocoa powder from the grocery store in any recipe requiring cocoa powder. It's never caused a noticeable problem - everything's turned out properly chocolaty and sweet.
And then one day, armed with a chocolate biscotti recipe, I saw a container of Valrhona cocoa powder on a shelf of my favorite specialty food store. I considered how much more a bar of Valrhona chocolate was than a bar of Hershey's, and suddenly began to question my cocoa powder tradition. I went ahead and splurged ($14 for 8.8 oz).
Valhrona is a French chocolate manufacturer, known for it's extreme devotion to quality, in both the selection of beans and production. More and more companies are have started making quality their primary concern, which is great for those of us who care deeply about our baked goods. Sharffen Berger is a great company to try, as are Penzeys and Pernigotti.
Cocoa powder is unsweetened chocolate, partially defatted and ground into a powder. Many recipes call for Dutch-processed cocoa, which means it's been treated with an alkali compound to remove its acidity. This deepens the flavor of the powder since the sugar in the recipe doesn't have to overcome the natural flavor of the cocoa.
And the biscotti? The difference was clear - the chocolate flavor was strong and rich, a much deeper chocolate than the cheaper cocoa powder produced. It was a simple way to significantly improve taste. The recipe can be found here on David Lebovitz's site.
Here are some other great ways to use the rest of your luxury cocoa powder: