Irish Slammer Magic Chocolate Cake {Guinness, Bailey’s, and Jameson Custard Cake}

Irish Slammer Magic Chocolate Cake. The cake with the magically separating custard and cake layers flavoured with Guinness Stout, Bailey's Irish Cream, and Jameson Whiskey.

Guinness has a weird effect on people. Most folks are pretty opinionated about it.  I’m firmly in the ‘love it’ camp but I know a lot of people who are -if not in the ‘hate it’ camp- decidedly lukewarm about it. Most of those in the ‘hate it’ and ‘meh’ camps, though, can at least find a modicum of love for it when it’s baked into things. How is this possible? Because Guinness equals malt and lots of it and chocolate pairs with malt like sunshine goes with lollipops.

And Guinness plus Bailey’s Irish Cream plus Jameson Whiskey? Well? That’s another combination that -while delicious- is a bit polarizing. Why? Well, it’s a drink that has kind of an awful name: The Irish Car Bomb. While working on this cake, I realized I was uncomfortable using that name, and so asked friends and family (not because they’re lushes, but because they’re knowledgeable) whether there was a widely known alternate name for the drink. One friend suggested “Irish Slammer” after some research. “BRILLIANT!” I said, “What could possibly be wrong with calling it an Irish Slammer?”

My brother chimed in with concern over the innuendo. “I don’t see any inuendo,” said I… and brushed off my little brother. So then today, while working on this post, I sent a note to my sister, the research librarian, about the cake. I said I wasn’t calling it an Irish Car Bomb because I found the name distasteful. She agreed. Then I told her I was going to use Irish Slammer but that our brother had said I might get comments on the innuendo. She said, “Really? I have no idea. Wait. I’m a librarian. I can look it up!”

Turns out our brother was right.  Who knew? I mean besides him?

…And whoops.

HOWEVER… I’m reclaiming this word to mean this particular cake. The cake that my sister suggested I title, “I’ve got booze and I’ve got chocolate. It’s cake time.” A little unwieldy, but appropriate. Probably  more appropriate than Irish Slammer, but hey. I was committed. I had my graphic on the photo already.

Other names we tried out, “Blandly Named Cake That No One Can Misconstrue”, “Inoffensive Cake”, “Offensively Divine Cake”, (or my other favourite from her) “Seemingly unassuming cake that’ll knock your socks off only in a consensual manner of course.”

… Shoot. My brain hurts. Just make the darned cake. It’s amazing. And inoffensive. Well, unless you’re morally opposed to booze in cake, then I’m just in trouble anyway. Just in time for St. Patrick’s Day: a heaping helping of my mental state.

I present to you The Cake Which Shall Not Be Named.

Irish Slammer Magic Chocolate Cake. The cake with the magically separating custard and cake layers flavoured with Guinness Stout, Bailey's Irish Cream, and Jameson Whiskey.

After all this, if you’re still with me and haven’t clicked away in a huff, you may be wondering why it’s a “magic” cake. This is because the cake batter separates into two distinct layers as it bakes. The underside is a perfectly smooth, rich malted chocolate, Irish cream, and whiskey custard reminiscent of the aforementioned drink while the top is a thin, light-as-air chocolate cake.

5 from 1 reviews
Irish Slammer Magic Chocolate Cake {Guinness, Bailey’s, and Jameson Custard Cake}
This cake inspired by and adapted from with thanks to Foodness Gracious's Chocolate Magic Cake Recipe which was inspired by the lovely Diane and equally lovely Todd of White on Rice's Magic Cake.
  • ½ cup unsalted butter, melted and cooled slightly
  • 1 cup whole milk
  • 1 cup Guinness stout
  • ¼ cup plus 2 tablespoons Bailey's Irish Cream
  • 2 tablespoons Jameson Whiskey
  • 1 cup all-purpose flour (4.25 ounces by weight)
  • ½ cup unsweetened cocoa powder (I use Dutch Process)
  • 4 eggs, separated
  • ⅛ teaspoon white or cider vinegar
  • 1¾ cups powdered sugar (6 ounces by weight)
  • ¾ teaspoon vanilla extract
  • ¼ teaspoon coffee extract (*See Notes)
For Garnish:
  1. Preheat your oven to 325°F. Grease an 8-inch square cake pan and set aside.
  2. Combine the beer, milk, and Irish cream in a saucepan and heat just until body temperature.
  3. In a small bowl, whisk together the flour and cocoa powder until evenly coloured and lump free.
  4. In a stand mixer fitted with a whisk attachment or a bowl with a hand mixer, beat the egg whites and vinegar on high until you reach stiff peaks. If using a stand mixer, scrape the egg whites into another bowl and proceed. If using a hand mixer, use a second bowl to proceed.
  5. Beat the egg yolks and sugar together until they are silky smooth and a lighter yellow. Beat in the butter until fully incorporated, then the flour and cocoa mixture until smooth. Pour in the beer mixture and the Jameson whiskey, and the extracts and beat that until totally smooth.
  6. Now is where it's going to look like you're going wrong, but I promise you're not. whisk about ⅓ of the egg whites into the cake batter with enthusiasm. It'll look like you're deflating the egg whites, but it's okay. Now, take the remaining ⅔ of the whipped egg whites and fold them in just until the big clumps of egg white are broken up and you have what looks to be very loose batter with little egg white bubbles floating around in it. It looks like a hot mess, but it'll all work out in the oven.
  7. Bake in your preheated oven for 50 minutes, or until the cake is set on top and still wiggly underneath, rather like a cheesecake should be. Let the cake cool at room temperature until you can comfortably handle the pan, then cover with plastic wrap and refrigerate until firm.
  8. Slice into squares and serve garnished with Bailey's (or plain) whipped cream, a dusting of cocoa powder, and a drizzle of chocolate sauce.
*If you cannot find coffee extract, you can simply substitute an equal amount of vanilla extract.


  1. says

    I’m at work, so I don’t really want to look up the real meaning of Irish Slammer. Aren’t you going to tell us? Please? I generally prefer my guinness in a cake unless I’m in Ireland, then I’ll drink it. So pass me a slice.

  2. CarrollWC says

    OK, this is definitely on the to-do list. My son used to work in a pub in Ireland. You can use powdered espresso (about a tablespoon) when you add the cocoa powder if you don’t have coffee extract. It helps bring out the chocolate flavor.

    • says

      I haven’t tested doubling it but I imagine it could be done… Of course you’d have to adjust cooking times. Let me know if you try it!

  3. Amy says

    Happy St. Patrick’s Day! I am so excited about this “magic” cake. At first I was intimidated to try a “magic” recipe, but it was really simple to assemble. I may have missed it, but I couldn’t find where I was supposed to put the vanilla/coffee extract in the directions, so I went ahead and mixed it in with the egg yolks and sugar. I just popped my cake into the oven. If it tastes as good as it smells, my husband is going to be in heaven. Oh, I did a little quality assurance check on the Bailey’s Whipped Cream. Delish!

  4. Geralyn Hoerauf says

    Yes, a year late to this party, but found this recipe searching for something different in a Guinness cake for St. Patrick’s Day. I multiplied the recipe by 1-1/2X for a 9″ X 11″ silcon pan. The result was AMAZING!! Still baked for 50 minutes and followed the recipe amounts (X1-1/2) exactly. So fudgy and moist with lots of chocolate flavor. Make this as often as your diet will allow!


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