Guinness isn’t just for drinking! This rich, moist chocolate cake is spiked with Irish stout for a deeply chocolatey flavour and subtle bittersweet edge. Baked in a thick, single layer and topped with fluffy vanilla malt buttercream to mimic a frothy pint of Guinness!
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Chocolate cake comes in many forms. You’ll find recipes containing coffee, mayonnaise, and even mashed potatoes. While the latter would be equally on-theme for Saint Paddy’s Day, today I’m sharing my luxuriously rich and fudgy Chocolate Guinness Cake!
Beer in cake, you ask? I know it sounds weird, but hear me out.
Why Bake with Guinness (Even if You Don’t Like it)
Chocolate cakes can taste a little one-note, but throw in some dark, creamy Guinness and suddenly we’ve got a bit of complexity.
In baking, Guinness acts as a flavour enhancer, especially when paired with chocolate, bringing out the natural richness and depth of cocoa. As the alcohol cooks off, it leaves behind malty, roasted, and subtly tangy undertones.
I assure you, this cake does not taste like beer, and you’re not going to be falling off your chair after eating a slice… or even two.
A Celebration Cake That’s Surprisingly Simple
This recipe was loosely inspired by Nigella Lawson’s Chocolate Guinness Cake, designed to emulate a pint of stout, with a dark body (the cake) topped with a pale, frothy head (the icing).
My version uses 100% oil to produce a cake that stays moist for up to 4 to 5 days. Unlike butter-based cakes, it won’t go dense or hard in the fridge! I’ve also incorporated melted chocolate in addition to cocoa powder for a fudgier taste and texture. If you don’t believe me when I say this cake is chocolatey, just check out how dark it is!
To complement the malty flavour profile of Guinness, I’ve paired this cake with a vanilla malt buttercream, flavoured with malted milk powder, and whipped until light and fluffy. I don’t like an overly sweet, heavy, or gritty buttercream, and I assure you this is none of those things.
My favourite thing about this cake is how unassuming it is. With just a single layer, it comes together quickly — you don’t even need a mixer for the batter — and yet it’s worthy of a place on the table at any gathering, birthday party, or Saint Patrick’s Day celebration.
What You’ll Need
For the chocolate Guinness cake
- Dark chocolate: use a block of good quality dark chocolate, such as Lindt or Nestle Plaistowe. I wouldn’t go any higher than 80% cocoa (I use 70%).
- Sugar: there’s a fair bit of sugar in this cake, but it’s needed to balance the bitterness. I typically use granulated sugar but caster sugar is fine too.
- Guinness: Guinness Extra Stout has a bolder flavour which works really well in baking. It’s pretty widely stocked in liquor stores in Australia. I’ve found it at BWS, Dan Murphy’s, and my local IGA. If you can’t track down some Extra Stout, Guinness Draught is bit milder and creamier, but it still works. You can even reduce it down to concentrate the flavour (see recipe notes for details).
- Cocoa powder: any natural, unsweetened cocoa will do! We’re going to bloom it in hot liquid (melted chocolate and stout) to really enhance its flavour.
- Vegetable oil: I normally like to include butter in my cake recipes for flavour, but in a rich chocolate cake like this you won’t be able to taste it under all the cocoa and stout. Using 100% oil keeps the cake super moist without any real flavour trade-off. You can substitute any neutral-flavoured oil you have on hand, such as sunflower oil or avocado oil.
- Sour cream: this is the (not-so) secret ingredient for a moist cake! Greek yogurt will work too if that’s what you have on hand. Measure the sour cream or yogurt and let it come to room temp first, or you can give it a quick 10-15 second zap in the microwave, just enough to take the chill off. If it’s too cold, you’ll end up with lumps in your batter.
- Eggs: use room temperature eggs and make sure the chocolate mixture has cooled before adding them, or they may scramble!
- Vanilla extract
- Plain flour: too much flour will make this cake dry and dense. I’m a big advocate for baking by weight, but if you don’t have a scale, the spoon-and-level method is your next best bet.
- Baking soda and baking powder: these give the cake a little lift and prevent it from turning out too dense or brownie-like.
- Salt
For the vanilla malt buttercream
- Unsalted butter: I always use unsalted butter when making buttercream so that I can control the salt levels, and I recommend you do the same! Make sure the butter is soft enough to leave an indent with your finger, but not so soft that it’s melting or greasy.
- Icing sugar: known as ‘powdered sugar’ in the US. Always sift it well before using.
- Malted milk powder: this is sold in tins and can be found at most supermarkets in the tea/coffee aisle. I use the plain, Nestle-branded one. You can use a chocolate version if you prefer, but you won’t get the same visual contrast of light icing against dark chocolate cake.
- Thickened cream: also known as ‘heavy cream’ or ‘whipping cream.’ It might seem counterintuitive, but adding cream actually makes buttercream lighter and fluffier because you can whip air into it — something you can’t do with milk!
- Vanilla extract: use pure vanilla extract for the best flavour. Imitation vanilla and vanilla essence taste too artificial, in my opinion.
- Salt
*For the full list of ingredients with measurements, see the recipe card below
How to Make Chocolate Guinness Cake
1. Prep – Start by preheating your oven to 180°C (160°C fan/350°F). Grease a 23 cm (9-inch) cake tin and line the base and sides with parchment paper — this is important to prevent sticking and keep the sides looking neat!
2. Heat the chocolate-stout mixture – In a medium saucepan, combine the chocolate, sugar, and Guinness. Heat, stirring frequently, until the chocolate has melted and the sugar has dissolved. Keep an eye on it, as it can bubble over. Remove from the heat.
3. Bloom the cocoa – Sift in the cocoa powder and whisk to combine. Allow the mixture to cool for 15-20 minutes.
4. Combine the dry ingredients – In a medium bowl, whisk together the flour, baking soda, baking powder, and salt. Set aside.
5. Mix the wet ingredients – Transfer the cooled chocolate-stout mixture to a large mixing bowl. Whisk in the vegetable oil, then add the sour cream, eggs, and vanilla, and whisk to combine.
6. Add the dry to the wet – Add the dry ingredients in batches, mixing in between each addition until just combined. It may look a little lumpy, but this is just bubbles from the carbonation.
7. Bake – Pour the batter into the prepared cake tin and tap on the countertop a couple of times to release air bubbles. Bake on the middle rack for 45-55 minutes. A toothpick inserted in the centre should come out mostly clean (a few moist crumbs are fine). If there’s wet batter, return the cake to the oven and check again in a few minutes.
8. Cool completely – Cool in the tin for 15 minutes then transfer to a wire cooling rack. Because this cake is quite dense and moisture-rich, it takes about 2-2.5 hours to cool completely.
How to Make Vanilla Malt Buttercream
1. Cream the butter – Add the softened butter to a large bowl and beat for 3-4 minutes, until pale and creamy.
2. Add icing sugar – Working in batches, sift in the icing sugar, mixing well between each addition.
3. Add cream and flavourings – Add the malted milk powder, vanilla, cream, and salt, and continue mixing for a couple more minutes, until the buttercream is light and fluffy. Adjust the consistency with a little more cream or icing sugar if needed.
4. Ice the cake – Use an offset spatula or a butterknife to spread a generous layer of buttercream on top of the cake. Finish with shaved chocolate, if desired. I use a vegetable peeler to create chocolate curls but you could also use a box grater or a microplane for finer shavings.
Why Did My Cake Sink in the Middle?
A slightly sunken middle is kind of a trademark of Guinness cake. A high ratio of wet ingredients, namely stout, oil, and sour cream, make this cake super moist and fudgy. However, it also means the batter leans quite liquid-y, and without much flour to provide support, the middle will naturally want to sink. On the bright side, you can simply level the top or use the extra space as a vessel for more buttercream.
That said, if your cake has a big, unsightly crater in the middle, something else has probably gone awry. Here are some common reasons your cake might sink:
- Over-mixing creates excess air bubbles which expand in the oven and then collapse, causing the cake to sink. Mix the dry ingredients into the wet just until there are no visible streaks of flour left.
- Opening the oven door too early introduces a rush of cold air which can cause the cake’s delicate centre to deflate. Wait until the final few minutes of baking to start checking!
- Under-baking means the centre hasn’t had a chance to set properly, and the cake will sink as it cools. Always check for doneness with a toothpick or skewer before removing it from the oven. If there’s any sign of wet batter, the cake needs a little longer.
* Please note: all cup measurements are approximate and based on Australian standard cups (250ml). For best results, weigh your ingredients with a kitchen scale.
Equipment
- 23 cm (9-inch) cake tin,
- saucepan
- hand mixer or stand mixer with the whisk attachment, for the buttercream
Ingredients
For the chocolate Guinness cake
- 80 g (2.8 oz) dark chocolate, plus more for decoration
- 330 g (1 ½ cups) granulated sugar, or caster sugar
- 250 ml (1 cup) Guinness, extra stout if possible, see notes
- 60 g (¾ cup) unsweetened cocoa powder
- 125 ml (½ cup) vegetable oil, or another neutral-flavoured oil
- 125 g (½ cup) sour cream, room temperature
- 2 eggs, room temperature
- 2 tsp vanilla extract
- 195 g (1 ½ cups, spooned and levelled) plain flour
- 1 tsp baking soda
- ½ tsp baking powder
- ¼ tsp salt
For the vanilla malt buttercream
- 200 g (⅘ cup) unsalted butter, softened
- 300 g (2 cups) icing sugar, sifted
- 6 tbsp malted milk powder
- 90 ml (⅜ cup) heavy cream
- 1 tbsp vanilla extract
- pinch of salt, optional
Instructions
Make the chocolate Guinness cake
- Preheat the oven to 180℃ (160℃ fan/350℉). Grease a 23 cm (9-inch) cake tin with butter or oil, then line the bottom and sides with parchment paper.
- To a saucepan, add the chocolate, sugar, and Guinness. Set over low-medium heat and bring to a gentle simmer. Cook, stirring frequently, until the chocolate has melted and the sugar has fully dissolved.
- Remove the saucepan from the heat and sift in the cocoa powder. Whisk together until smooth, then set aside to cool for 15-20 minutes.
- Whisk together the flour, baking soda, baking powder, and salt, and set aside.
- Pour the cooled chocolate mixture into a large mixing bowl. Add the oil and whisk until smooth and shiny. Add the sour cream, eggs, and vanilla, and whisk to combine.
- Gradually add the dry ingredients to the wet, being careful not to over-mix.
- Pour the batter into the prepared cake tin and give it a couple taps on the countertop to release any large air bubbles. Bake on the middle rack for 45-55 minutes, or until a toothpick inserted into the centre comes out with just a few moist crumbs. A slight dip in the centre of the cake is normal (see note 5).
- Allow the cake to cool in the tin for 15 minutes, then carefully remove and transfer to a wire rack. Make sure it's completely cool before icing with buttercream.
Make the vanilla malt buttercream
- Place the softened butter in a mixing bowl, or the bowl of a stand mixer. Beat for 3-4 minutes until pale and creamy.
- Sift in the icing sugar a little at a time, beating in between until incorporated. Stop to scrape down the sides of the bowl as needed.
- Add the malted milk powder, cream, vanilla extract, and salt. Beat until smooth and fluffy. If it's too thick or too thin, adjust with a little more icing sugar or cream until it reaches your desired consistency.
- Spread an even layer of buttercream over the top of the cooled cake. Garnish with chocolate shavings, if desired!
