The butter and sugar are happily creaming in my mixing bowl, the oven's preheating, and I'm already dreaming of freshly baked chocolate cookies. But when I open the cupboard, I'm faced with a rude, snack-inhibiting reality. Where I thought was a box of cocoa powder is a stack of saltines and a half-empty jar of peanut butter.
Denial enters stage left. "You don't really need that ingredient, do you? Just use this totally and completely different ingredient instead. No one will even notice!" Despite Denial's coaxing tone, I know that I've got to go to the grocery store.
When it comes to most ingredients for baking, substitutions can be tricky since recipes are formulated based on very specific ratios and chemical interactions. With cocoa powder and unsweetened chocolate, there are few tricks (aka: mathematical formulas...but "tricks" sounds more fun) that you can use in a pinch, but as a general rule, substituting is not recommended. Here's why.
Let's Review our Ingredients
Cocoa powder is the dry solid remains of fermented, dried, and roasted cacao beans. The beans are cracked into nibs, which are then ground to a paste made of cocoa solids suspended in cocoa butter. Once processors extract the butter they're left with the crumbly solids, which are then ground into a fine powder. Cocoa powder comes in two different forms: natural and Dutched. Natural cocoa powder retains the cacao's natural acidity, while Dutched is neutralized with an alkaline chemical. As a result, Dutched cocoa is less acidic and has a darker color and more mellow flavor. (More on the difference here)
Once you know what cocoa powder is, you can understand how it works in baking. It's low in fat, contains high concentrations of cocoa solids, and sometimes brings acidity to a recipe.
Like cocoa powder, unsweetened chocolate originates from a paste made from ground cacao beans. But unlike cocoa powder, unsweetened chocolate keeps its cocoa butter. Simply put, unsweetened chocolate is a chocolate bar with 0% sugar and 100% cocoa. Because it's made from the whole, ground bean, it naturally contains both cocoa solids and fat (it's about 55% cocoa butter).
Can You Easily Substitute One for the Other?
The short answer is no.
The long answer is you could, but it's tricky and generally not recommended. Here's why.
Cocoa powder is lower in fat and higher in nonfat cocoa solids than unsweetened chocolate. That means it's more concentrated with cocoa flavor, so to get the same final chocolate flavor in a recipe, you'll need less cocoa powder than unsweetened chocolate. But substituting one for the other means you're changing mass and the amount of fat in a recipe, which, if you don't factor into your changes, could spell trouble for your dessert. (See a workaround below.)
To put the unsweetened chocolate/cocoa powder substitution to the test, I mixed two batches of old fashioned chocolate sugar cookies. One batch followed the recipe's instructions to use cocoa powder,sifted into the dry ingredients; in the second, I substituted the weight of cocoa powder for melted, unsweetened chocolate and added it to the creamed butter and sugar. Otherwise I left the ingredients as-is, without adjustments to the recipe's overall fat content.
The cookie made with cocoa powder was much darker and tasted more chocolatey, while the cookie made with unsweetened chocolate came out bland by comparison. Why? Not enough cocoa solids to flavor the cookies, and without cocoa's bitter edge, the cookies were too sweet.
The unsweetened chocolate cookie was also more cakey and crumbly than the cocoa powder cookie. While the cocoa powder cookie had a nice chew and slight snap, the unsweetened chocolate had a soft bite with crumb that seemed to disintegrate and become sand-like in my mouth. Why? Fat: unsweetened chocolate is full of it, and too much fat in a cookie can prevent the gluten in flour and proteins in eggs from holding the cookie together.
Even if you adjust the fat content, in a recipe, swapping out some butter to compensate for added cocoa butter, the results won't be quite the same. Different fats have different structural and melting characteristics, and they all can affect how a cookie crumbles, so to speak.
By the way, this is why high-fat, low-moisture desserts like cookies often call for cocoa powder instead of melted chocolate: cocoa delivers a bigger and more balanced chocolate bite without messing up the cookie's fat content.
But if You Have to Substitute...
While I don't recommend substituting chocolate for cocoa in a recipe (or vice versa), you can do it if you have to. The trick is to adjust your ratios to compensate for the higher concentration of cocoa solids in cocoa powder and the added fat in unsweetened chocolate.
Baking guru Paula Figoni is associate professor at Johnson & Wales, a former food scientist at Pillsbury and Ocean Spray, and the author of How Baking Works: Exploring the Fundamentals of Baking Science, made a simple equation to help that's based on fractions calculated from the amount fat naturally present in cocoa powder (10 to 12%) and unsweetened chocolate (50 to 60%). The formula assumes that 1 pound of unsweetened chocolate is equal to 10 ounces of cocoa powder plus 6 ounces of fat. The final recipe results won't be identical, but will make something reasonably tasty.
Weight of Unsweetened Chocolate x 5/8 = amount of needed cocoa powder
Weight of Unsweetened Chocolate x 3/8 = amount of needed additional fat
In other words, if a recipe calls for for 200 grams of unsweetened chocolate, multiply that quantity by 5/8, which equals 125. To determine the amount of additional fat needed, multiply 200 times 3/8 to get 75. Therefore, the adjusted recipe would use 125 grams of cocoa powder and 75 grams of fat. Since most people don't have pure cocoa butter in the cupboards, your best alternative is shortening, which is low in moisture, bland like cocoa butter, and melts in a similar way.
So, if you're in a pinch and must make a substitution, this formula will do the trick for any recipe from pudding to cake. Give the equation a try! But if you're not into slide rules and left your TI-83 in the 10th grade, make life easier and head to the grocery store.