That’s a very good question, reader Erika. To tell the truth I can’t think of many, other than that it allows the baker to hijack some exotic cacao flavors that are normally reserved for professional bakers or candy makers. Your typical supermarket might stock two or three types of unsweetened cocoa powder. Here in the States it’s usually Hershey and Droste, possibly Valrhona or Scharffen Berger if the store has an upscale clientele. These of course represent only the tiniest fraction of the powders that are available in the wider cocoa universe. Most of these never see the light of day in the retail world, and are only sold in large quantities to commercial bakers and confectioners. Baking with bar chocolate — expensive as it can be — equals the playing field a bit — at least for the true chocolate epicure.
So there’s that. But otherwise bar chocolate doesn’t offer any specific functional benefits that I can think of. Chocolate is made up of — mainly — three things: cocoa solids, cocoa butter and sugar. Milk solids are generally in the mix in some proportion and most chocolate makers include a flavoring or two like vanilla. Cocoa solids (albeit of middling quality) are available everywhere, as is sugar, milk (solids and liquid) and vanilla. Cocoa butter is harder to find, though it’s ultimately nothing more than a flavorless fat. Granted it’s a fat that’s a firmer at room temperature than say butter, but firmness isn’t necessarily an advantage in a cake.
So no, Erika, other than adding more exotic chocolate flavors to a cake I’m hard pressed to think of a particular benefit of bar chocolate. My wife and daughters like to lick the leftovers off the spoons, spatulas and bowls of course when I’m done mixing. They’d definitely call that a benefit if you asked them. Thanks for the question!