My Goals

  • Assertive, complex chocolate flavor in the cake

  • Simple, quick method

  • Creamy frosting with lighter chocolate flavor to contrast with the cake

Sheet cakes don’t require the work that goes into making layer cakes; they are simply spread with a thick coat of frosting and served straight from the pan. When the results are good, a sheet cake yields great reward for the effort. But most versions I’ve made are dry and crumbly, have barely a whisper of chocolate flavor, or are so dense that they verge on brownie territory. Loose, drippy frostings make cakes too messy to eat out of hand, while stiff, fudgy ones weigh down the crumb; more often than not, they’re cloyingly sweet, too.

The kind of chocolate sheet cake I could turn to again and again would boast a tender, moist, sturdy crumb that was seriously chocolaty and a silky chocolate frosting just sweet enough to stand apart from the flavor of the cake. It would come together with baking staples and basic equipment—no mixers or food processors needed.

When Chocolate Cake Became Chocolate

American chocolate cake as we know it—one that contains chocolate, cocoa powder, or both—is a relatively young dessert. The term “chocolate cake” originally referred to a yellow or vanilla cake that was served with a chocolate beverage. Only once chocolate became cheaper, around 1940, did home cooks start baking with large amounts of cocoa and recipes for truly chocolaty cakes come about.

Cocoa Loco

Some recipes for chocolate cake call for cocoa powder but no bar chocolate, but we’ve found that using both produces cakes with deeper chocolate flavor. That’s because, ounce for ounce, cocoa powder packs more chocolate flavor than any other form of chocolate, while bar chocolate adds complexity, fat, and sugar.

We started by sampling a number of chocolate cake recipes using varying amounts of cocoa powder and chocolate, many of which fell short of our expectations.

In fact, when I made a series of chocolate cakes to get my bearings, the one with the fullest chocolate flavor contained plenty of both—¾ cup of cocoa powder and 8 ounces of melted bittersweet chocolate. That recipe didn’t specify which type of cocoa to use, natural or Dutch-processed, but I used the latter. We reserve Dutch-processed cocoa, which tends to be more expensive, for recipes where cocoa makes up a significant portion of the batter because we’ve found that its flavor is more complex and balanced than that of natural cocoa; “Dutching” refers to processing the cocoa with an alkali that neutralizes its natural acidity.

To make a basic chocolate cake batter, I melted butter with the chocolate and added the cocoa powder so that its flavor molecules would release fully (or “bloom”). Then I whisked eggs with sugar; added the butter-chocolate-cocoa mixture, milk, and vanilla; and whisked in the dry ingredients (flour, salt, and baking soda) until a smooth batter formed. This “dump-and-stir” method is fast and easy and also produces a less crumbly cake than the creaming method. In that method, flour is combined with creamed butter and sugar alternately with liquid, so some of the flour becomes coated in fat and thus can’t interact with water to form gluten. And the less gluten, the more crumbly the cake.

I poured the batter into a greased 13 by 9-inch baking pan, which would produce a higher ratio of cake to frosting than a baking sheet would. I baked it at 325 degrees for about 30 minutes. It wasn’t too sweet, but despite loading up the batter with cocoa and chocolate, it lacked the chocolate punch and depth that I was hoping for.

Fortunately, trading the melted butter for vegetable oil solved that; its neutral flavor produced a cleaner-tasting cake that allowed the chocolate to shine. I also saved myself a couple of bowls to wash by mixing the dry and wet ingredients into the saucepan where I’d heated the chocolate mixture.

Science: Dry Cake? Check Your Cocoa


There are two types of unsweetened cocoa powder: natural and what is known as Dutch-processed. The Dutch-processed kind is often more expensive, but for recipes that call for a hefty amount of cocoa powder (more than ½ cup), it is worth seeking out. For one thing, Dutched cocoa has been neutralized with alkali to take away some of the cacao bean’s harsher, more acidic notes. But here’s another, far less well-known reason: Dutched cocoas typically have far more fat than natural cocoas, sometimes twice as much. Fat adds a perception of moisture in baked goods. In addition, cocoa powders with more fat contain less starch. Why is that important? Starch absorbs free moisture in a batter, so the crumb bakes up drier. In fact, the starches in cocoa powder absorb up to 100 percent of the powder’s weight. (Compare that with the starches in flour, which can absorb only 60 percent of the flour’s own weight.) This helps explain why we found our cake to be noticeably moister when made with Dutched rather than with natural cocoa powders.

But not just any Dutched cocoa will do, since fat percentages vary. Our recommended cocoa from Droste contains 22 percent fat. Compare that with the 11.9 percent in Equal Exchange Dutch Processed Cocoa Powder, an amount that’s similar to those of most natural cocoas. The takeaway: In baked goods that call for a higher proportion of cocoa powder, we’ll be calling for higher-fat Dutch-processed cocoas not just for their rounder flavor but also for the moist texture they provide.

Dutched Cocoa

Free moisture does not get bound up with the starches, so the cake is more moist.

Natural Cocoa

Free moisture gets bound up with the higher level of starches, so the cake is drier.

Before focusing on the frosting, I made the cake with natural cocoa, just to check that it worked. I’d expected this cake to be paler (Dutching raises the pH of cocoa, darkening its color) and a bit less complex in flavor, but what caught me by surprise was its noticeably drier crumb. To be sure that I hadn’t overbaked the cake, I made several more, using multiple natural cocoas, and was met with the same dry result each time. It wasn’t until I did some digging about cocoa—including talking to Clay Gordon, the creator and moderator of thechocolatelife.com, a clearinghouse for chocolate information—that I understood the problem: In addition to being more acidic than Dutch-processed cocoas, most natural cocoas are much lower in fat, which makes them very absorbent. In essence, the low-fat natural cocoas were robbing the cake of moisture. I’d be sticking with the Dutch-processed cocoa for sure.

Icing on the Cake

A simple sheet cake deserves an equally simple frosting—one that can be stirred together while the cake bakes. That eliminated buttercreams, which require hauling out a stand mixer or food processor. For something creamy and spreadable, I considered a ganache. This frosting often takes the form of a pourable glaze of melted chocolate and cream, sometimes gilded with softened butter. But ganache can range from soupy to stiff, depending on the ratio of cream and butter to chocolate, so I would adjust the ratio of those ingredients until I had something thick and creamy.

For a satiny, spreadable frosting that comes together easily, we experimented with different ratios of cream, butter, and chocolate until we found the perfect consistency.

One recipe I’d tried called for spreading the cake with a milk chocolate ganache, the lighter flavor of which countered the darker cake nicely. Riffing on this idea, I landed on ⅔ cup of cream heated with a pound of chocolate; the high proportion of chocolate gave me a thicker ganache than most standard recipes. I then added 2 sticks of softened butter, which lent it body and made it spreadable at room temperature. But waiting for my frosting to cool took 2 to 3 hours, so I refrigerated it, which cooled it down within an hour so that it was ready to use when the cake finished cooling. Then I gave the mixture a good whisk, which made it smooth and creamy, before slathering a thick layer of it over the cake.

The dark, complex cake and milky-sweet, satiny frosting was a combination that I knew would tempt both milk and dark chocoholics alike. And since it comes together with baking staples and an unfussy, appliance-free mixing method, this is a chocolate cake built for any cook and any occasion.

Keys to Success

  • Assertive, complex chocolate flavor in the cake

    Cocoa powder gives the cake pure, assertive chocolate flavor; we use the Dutch-processed kind because it’s less acidic and because most Dutch-processed cocoas (such as Droste) contain much more fat than natural cocoas and thus make for a moister crumb. “Blooming” the cocoa by heating it with the chocolate and milk boosts its flavor. Melted bittersweet chocolate adds complexity as well as fat and sugar, and using neutral oil instead of butter lets the chocolate flavor shine.
  • Simple, quick method

    To save time and dishes, we mix the batter in the same saucepan used to melt the chocolate.
  • Creamy frosting with lighter chocolate flavor to contrast with the cake

    Unlike a labor-intensive buttercream, chocolate ganache comes together quickly in a saucepan. Adding plenty of softened butter to the chocolate-cream mixture gives it thick, rich body, and whisking the ganache after it has cooled makes it smooth and light. Milk chocolate provides a sweet contrast to the darker chocolate cake.