Guinness cake is moist, chocolaty, and easy to make. There’s just one problem: It never actually seems to taste like Guinness.
I recently tested five different popular recipes for the cake in the test kitchen, and while my colleagues appreciated their flavors and textures, no one could identify the Irish stout in any of the samples.
And that’s a shame, because on paper, the beer’s malty, caramelly flavor and edge of smoke sound like the perfect partner for decadent dark chocolate. So, I made it my mission to find a way to capture both intense chocolate flavor and Guinness’s signature profile in one cake.
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Guinness cake is typically a single layer topped with a thick pillow of cream cheese frosting, evoking the foam on top of a pint. The cake is a simple dump-and-stir process, with no fussy technique or equipment needed.
My first instinct when it came to imparting more Guinness flavor was, naturally, to double down on the beer—but adding more required that I cut back on one of the other liquid components in the formula (milk, oil, or sour cream) to keep the batter from becoming too wet.
Those ingredients all contribute essential fat to the cake, so when I reduced their quantities the cake became too dry and lean. Reducing the beer to a concentrated syrup on the stovetop helped, but it took time and added a complicating step to this otherwise dead-simple cake.
Guinness Flavor, Compound by Compound
To amplify the Guinness flavor in the cake, we looked into the beer’s chemistry, searching for ingredients that shared its flavor compounds. The stout gets much of its flavor from roasted barley malt, as does malted milk powder. Maltol, a flavor compound in Guinness with a caramelly, toffee-like character, is also found in brown sugar. Guinness’s methylbutanal (woody and cocoa-y) and guaiacol (smoky) both show up in molasses as well. By adding these three ingredients to the cake, we were able to create more Guinness flavor without adding more Guinness and making our batter too runny. —Paul Adams
Adding more Guinness was out.
What if instead I modified my recipe to include other ingredients that replicated and amplified the various flavors of the beer? After consulting with our science research editor about the specific flavor compounds in Guinness, I devised a plan: I’d substitute brown sugar and molasses for the granulated sugar commonly found in the cake to add the malty-smoky notes and use malted milk powder for those caramelly flavors.
The results were well worth raising a pint: a dense, moist cake rich with dark chocolate and cocoa and scented with the unmistakable flavors of Guinness.
Thicker, Creamier Cream Cheese Frosting
Cream cheese frosting is a great foil for chocolate cake—but many recipes yield an overly sweet frosting and/or a grainy one. This happens because the mixing process warms the frosting’s cream cheese and butter, liquefying their fat and making the frosting runny. To counteract that, cooks often add more powdered sugar, oversweetening the frosting and creating a grainy texture in the process. Here, we wanted a thick, creamy frosting that could hold its shape and evoke the airy foam on the top of a pint and that also wouldn’t overpower the meticulously balanced flavors of the cake. Here’s how we achieved it.
- Add the ingredients fridge-cold: Starting with fridge-cold cream cheese and butter gives you more time to mix before they get too soft, allowing you to whip the frosting to a light, creamy, and smooth texture without having to add extra sugar.
- Use extra butter: Making this frosting more butter-heavy than a typical cream cheese frosting makes it a little extra savory, balancing its sweetness. Replacing some of the cream cheese with butter also makes it thicker and more stable, as butter contains less water than cream cheese.
- Incorporate malted milk powder: A few teaspoons imbues the frosting with subtle toasty maltiness, instantly making it more beer-like.
This cake deserved a topping that would complement, but not mask, the delicate flavor balance I had worked to achieve.
For this, I deviated from the traditional approach to a cream cheese frosting by increasing the butter relative to the cream cheese, reducing the sugar, and adding malted milk powder to reflect the flavors in the cake.
Working with cold rather than room-temperature butter and cheese gave me more time to whip up a light, creamy, and smooth frosting before the butter and cream cheese got too warm.
The not-too-sweet frosting swirls effortlessly on the cake, providing the perfect light-tangy contrast to the cake’s deep, dark complexity.
Chocolate Guinness Cake with Malted Cream Cheese Frosting
Stout and chocolate are a perfect pair—but it takes chemistry to make both shine in this moist, fudgy cake.
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