Yogurt makes this cake nice and moist. I
normally use whole milk plain yogurt (Greek style) as I like its rich and
tangy flavor. However, if you are using a lower fat yogurt, I would drain
it first to remove any excess water.
This cake also contains a flavorless oil
instead of butter. You can use
vegetable, corn, safflower, canola, or a light olive oil. The oil, along with the yogurt, gives the cake its moist texture, plus it will
keep the cake from becoming too firm (unlike butter) if you store it in
the refrigerator.
The chocolate flavor comes from unsweetened cocoa powder. My preference
is to use Dutch processed unsweetened cocoa powder (Valrhona and Droste
are a few good brands to try), but you could use natural unsweetened. And
remember, the flavor of the unsweetened cocoa powder does vary both by
brand and type. I also added a little instant espresso (or coffee) powder
as it enhances the chocolate flavor. For the chocolate chips, you can use
semi sweet, bittersweet, milk, and/or white chocolate chips. You can
leave them out but chocolate chips add a more complex chocolate flavor to
the cake, plus adds a nice crunch (if you are eating the cake cold).
