Perfect Guinness Chocolate Cake with Cake Mix

If you ask me, combining Guinness and chocolate is one of the best flavor pairings out there.

This easy chocolate cake starts with a boxed mix but tastes like you spent hours in the kitchen. The Guinness adds a rich, malty depth that makes the chocolate taste even more intense without any bitter beer flavor coming through.

It’s topped with a smooth chocolate ganache made from cream and chocolate chips that sets up into a glossy coating. A layer of buttercream frosting underneath adds extra sweetness and keeps everything nice and moist.

It’s a showstopper dessert that’s actually simple to pull off, perfect for birthdays or any time you want to impress your guests.

What Kind of Beer Should I Use?

For this recipe, Guinness is the classic choice and what gives the cake its signature deep flavor, but you don’t have to be too strict about it. Any dark stout or porter will work well and bring that rich, slightly bitter note that pairs perfectly with chocolate. If you’re not a fan of heavy beers, you can even use a lighter stout or amber ale, though the flavor will be a bit milder. Just avoid using anything too hoppy like an IPA, as that bitterness doesn’t play as nicely with chocolate. And don’t worry if your beer is flat or you’ve had it open for a day – it’ll still work just fine in the batter.

Options for Substitutions

This cake is pretty forgiving when it comes to swaps, so here are some options if you need them:

• Guinness beer: If you don’t have Guinness on hand, any dark stout or porter will work great. You can even use a lighter beer, though you’ll lose some of that rich, malty flavor. For a non-alcoholic version, try using strong brewed coffee or root beer.
• Oil: Vegetable oil is standard, but you can swap it for canola oil, melted coconut oil, or even melted butter for a richer taste.
• Eggs: For each egg, you can substitute with 1/4 cup applesauce or mashed banana, though the texture will be slightly denser. Flax eggs (1 tablespoon ground flaxseed mixed with 3 tablespoons water per egg) work too for a vegan option.
• Buttercream frosting: Store-bought is convenient, but you can make your own with butter, powdered sugar, and a splash of milk. Cream cheese frosting also pairs wonderfully with this chocolate cake.
• Chocolate chips: Semi-sweet chips are typical, but dark chocolate, milk chocolate, or even chopped chocolate bars work just fine. Just chop larger pieces into chip-sized bits.
• Cream: Heavy cream is best for the ganache, but you can use half-and-half in a pinch. Just know it won’t be quite as thick and rich.

Watch Out for These Mistakes While Baking

The biggest mistake when baking with beer is letting it go flat before adding it to your batter – use a freshly opened Guinness for the best flavor and texture since the carbonation helps create a lighter crumb.

Don’t skip the crumb coat step (that thin layer of frosting before chilling), as it traps loose crumbs and gives you a smooth surface for the ganache to flow over evenly.

When making the chocolate ganache, avoid overheating the cream and chocolate chips in the microwave, which can cause the mixture to seize up and turn grainy – stop as soon as the chips are mostly melted and stir until smooth.

Make sure your cake layers are completely cool before frosting, otherwise the buttercream will melt and slide right off, and let the ganache cool for about 5 minutes before pouring so it’s thick enough to coat the cake without running off too quickly.

What to Serve With Guinness Chocolate Cake?

This rich chocolate cake is pretty decadent on its own, so I like to serve it with something that cuts through the sweetness a bit. A scoop of vanilla ice cream or some lightly sweetened whipped cream works perfectly, especially if you serve the cake slightly warm. Fresh berries like raspberries or strawberries are another great option since their tartness balances out the chocolate and beer flavors. For a fun adult twist, you could even serve small slices alongside Irish coffee or a glass of cold milk for the kids.

Storage Instructions

Store: This cake stays moist and delicious for days! Keep it covered with a cake dome or plastic wrap at room temperature for up to 2 days, or in the fridge for up to 5 days. The buttercream frosting actually helps seal in all that moisture from the Guinness.

Freeze: You can freeze this cake for up to 3 months, either as a whole cake or in individual slices. Wrap it tightly in plastic wrap, then in aluminum foil to prevent freezer burn. I like to freeze slices separately so I can grab just one whenever a chocolate craving hits!

Serve: If you’ve refrigerated the cake, let it sit at room temperature for about 30 minutes before serving so the frosting softens up. Frozen slices can thaw in the fridge overnight or at room temperature for a couple hours.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 6600-7200
• Protein: 34-40 g
• Fat: 340-380 g
• Carbohydrates: 840-940 g

Ingredients

For the cake:

• 4 eggs (room temperature, about 70°F for better emulsion)
• 1/2 cup oil
• 12 oz beer (I use Guinness Draught for the most authentic flavor)
• 1 box cake mix (I always use Duncan Hines Devil’s Food for extra moistness)
• 1 teaspoon vanilla extract

For the assembly:

• 4 cups buttercream frosting

For the ganache:

• 2 cups cream
• 2 cups chocolate chips (I prefer Ghirardelli 60% cacao bittersweet chips)

Step 1: Prepare Pans and Mix the Batter

• 4 eggs
• 1/2 cup oil
• 12 oz beer
• 1 box cake mix
• 1 teaspoon vanilla extract

Preheat your oven to 350°F and grease two 9-inch round cake pans (or similar size), then line the bottoms with parchment paper for easy removal.

In a large mixing bowl, combine the room temperature eggs, oil, and Guinness beer, whisking until well combined and slightly foamy—the room temperature eggs will emulsify better with the liquid ingredients, creating a smoother batter.

Add the cake mix and vanilla extract, stirring until just combined; don’t overmix, as this can develop too much gluten and make the cake tough.

I always use Duncan Hines Devil’s Food because it adds extra richness that complements the beer’s deep flavors beautifully.

Step 2: Bake the Cake Layers

• batter from Step 1

Divide the batter evenly between the prepared pans and smooth the tops with a spatula.

Bake at 350°F for 28-32 minutes, or until a toothpick inserted in the center comes out with just a few moist crumbs—this ensures the cake stays tender rather than becoming dry.

The Guinness adds moisture to the batter, so don’t overbake or the beer’s subtle flavors will be lost to dryness.

Step 3: Cool the Cakes and Prepare the Frosting

• 4 cups buttercream frosting

Remove the cakes from the oven and let them cool in the pans for 10-15 minutes until they’re firm enough to handle, then turn them out onto wire racks to cool completely (about 1-2 hours).

While the cakes cool, prepare your buttercream frosting according to package directions or your preferred recipe, ensuring it reaches a smooth, spreadable consistency.

Step 4: Assemble and Crumb Coat the Cake

• cooled cake layers from Step 3
• buttercream frosting from Step 3

Place one cooled cake layer on your cake plate or turntable.

Spread a generous layer of buttercream frosting from Step 3 on top, then carefully stack the second cake layer on top.

Apply a thin, even crumb coat of frosting over the entire cake to seal in any loose crumbs, then refrigerate for 20 minutes—this base layer prevents crumbs from mixing into your final frosting layer.

Step 5: Make the Ganache and Final Frost

• 2 cups chocolate chips
• 2 cups heavy cream

While the cake chills, make the ganache by combining the chocolate chips and heavy cream in a microwave-safe bowl.

Microwave in 30-second intervals, stirring between each interval, until the mixture is smooth and pourable (usually 1-2 minutes total)—this gentle method prevents the chocolate from seizing or becoming grainy.

Pour the ganache over the chilled cake, allowing it to cascade down the sides naturally.

Let any excess drip onto a plate beneath the cake, then move the cake to its final serving plate once the dripping slows.

Step 6: Chill and Serve

Refrigerate the finished cake for 30 minutes to allow the ganache to set and the layers to come together.

Slice with a sharp knife warmed under hot water between cuts for clean edges.

I find that letting the cake sit at room temperature for 10-15 minutes before serving brings out the complexity of the Guinness flavor and softens the ganache for a better eating experience.

Perfect Guinness Chocolate Cake with Cake Mix

Delicious Perfect Guinness Chocolate Cake with Cake Mix recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 25 minutes mins

Cook Time 55 minutes mins

Total Time 1 hour hr 20 minutes mins

Servings 10 slices

Calories 6900 kcal

Ingredients

  

For the cake::

• 4 eggs (room temperature, about 70°F for better emulsion)
• 1/2 cup oil
• 12 oz beer (I use Guinness Draught for the most authentic flavor)
• 1 box cake mix (I always use Duncan Hines Devil's Food for extra moistness)
• 1 teaspoon vanilla extract

For the assembly::

• 4 cups buttercream frosting

For the ganache::

• 2 cups cream
• 2 cups chocolate chips (I prefer Ghirardelli 60% cacao bittersweet chips)

Instructions

 

• Preheat your oven to 350°F and grease two 9-inch round cake pans (or similar size), then line the bottoms with parchment paper for easy removal. In a large mixing bowl, combine the room temperature eggs, oil, and Guinness beer, whisking until well combined and slightly foamy—the room temperature eggs will emulsify better with the liquid ingredients, creating a smoother batter. Add the cake mix and vanilla extract, stirring until just combined; don't overmix, as this can develop too much gluten and make the cake tough. I always use Duncan Hines Devil's Food because it adds extra richness that complements the beer's deep flavors beautifully.
• Divide the batter evenly between the prepared pans and smooth the tops with a spatula. Bake at 350°F for 28-32 minutes, or until a toothpick inserted in the center comes out with just a few moist crumbs—this ensures the cake stays tender rather than becoming dry. The Guinness adds moisture to the batter, so don't overbake or the beer's subtle flavors will be lost to dryness.
• Remove the cakes from the oven and let them cool in the pans for 10-15 minutes until they're firm enough to handle, then turn them out onto wire racks to cool completely (about 1-2 hours). While the cakes cool, prepare your buttercream frosting according to package directions or your preferred recipe, ensuring it reaches a smooth, spreadable consistency.
• Place one cooled cake layer on your cake plate or turntable. Spread a generous layer of buttercream frosting from Step 3 on top, then carefully stack the second cake layer on top. Apply a thin, even crumb coat of frosting over the entire cake to seal in any loose crumbs, then refrigerate for 20 minutes—this base layer prevents crumbs from mixing into your final frosting layer.
• While the cake chills, make the ganache by combining the chocolate chips and heavy cream in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each interval, until the mixture is smooth and pourable (usually 1-2 minutes total)—this gentle method prevents the chocolate from seizing or becoming grainy. Pour the ganache over the chilled cake, allowing it to cascade down the sides naturally. Let any excess drip onto a plate beneath the cake, then move the cake to its final serving plate once the dripping slows.
• Refrigerate the finished cake for 30 minutes to allow the ganache to set and the layers to come together. Slice with a sharp knife warmed under hot water between cuts for clean edges. I find that letting the cake sit at room temperature for 10-15 minutes before serving brings out the complexity of the Guinness flavor and softens the ganache for a better eating experience.