Epic Chocolate, Porter & Potato Cake


Anyone have any leftover mashed potatoes? It is rare that we have them leftover, usually gobbling them all up without a second thought. Yet it does occasionally happen. Truth be told I have started making ridiculous amounts of mashed potatoes when I actually do make them, for a couple of reasons. First of all, we have bee known to eat a whole bunch of mashed potatoes in one sitting. Second reason, I am always hoping there will be leftovers so that I can make them into potato farls the next day. And now I have another reason to scheme for leftovers. Believe it or not, I used leftover mashed potatoes in this Epic Chocolate, Porter & Potato Cake. Epic is the perfect word to sum up how I feel about this cake. Rich, chocolatey, moist and delicious! And with spuds and porter as featured ingredients, what cake could better boast of its Irish origins.


I found this recipe at Bibliocook, the blog of award-winning Irish food writer and broadcaster, Caroline Hennessey. If you haven’t stopped by this great blog, you really must go take a peek. Caroline’s husband is one of the owners and brewers at Eight Degrees Brewing.  I first tasted one of their beers a couple of years ago at the Dingle Food Festival . My friend Theresa, being a fan of that craft brew, had brought along several of their beers for my husband and I to sample and we were instantly hooked. We are eagerly awaiting Eight Degrees arrival in the States. Make sure you keep it in mind if you are planning a trip over to Ireland. Indeed Caroline recommends that their Knockmealdown Porter, be the porter used in this Epic cake. And believe you me, I really wish I could have gotten ahold of a bottle, but alas, none was to be found in Virginia. So I decided to go with a locally brewed porter, looked to Baltimore Maryland (only about 1 hr or so away) and settled on DuClaw Brewing Company’s Sweet Baby Jesus Chocolate Peanut Butter Porter, a decision which I am not second guessing after tasting this amazing cake. All of the malty, chocolate, espresso and peanut butter notes of that porter really shine through in every decadent forkful.


I love that this cake is really no fuss/no-nonsense. It comes together quickly and easily. And since Caroline had mentioned that its taste improves a bit with age, I made it the day before I was planning to serve it and then just frosted it before folks arrived. And even though I frosted the entire cake, it really isn’t necessary. I think simply spreading a thick pillowy cloud of that cocoa dusted cream cheese filling would be sheer perfection. So why did I frost the entire cake? Well, it looks like it is time for a true confessions moment. The original recipe called for a 23cm round cake tin. Of course here in the States, we never really got into that metric system thing and still do everything in inches. I quickly figured out that 23 cm is a 9″ pan. However, I grabbed a cake pan that was only 1 1/2″ tall. It really needed to be at least 2″, so there was a bit of batter overflow happening when I baked it. No big deal as I had the cake tin sitting on a baking sheet, which caught the spillage. However, the edge of my cake ended up looking a bit raggedy. So I made the executive decision of covering my mistake with that scrumptious frosting and no one would be the wiser. Which they weren’t…until I spilled the beans here. Oh well, live and learn and always use taller cake tins when possible!


I served this substantial cake up at one of my husband’s band rehearsals and it easily fed a flock of hungry musicians, some of whom had seconds, raving about it all the while. I guess I do have even more of a reason to make extra mashed potatoes now. I’m going to have to arrange to have 20 lb. sacks delivered to my home soon if I’m not careful. The 5 lb. ones just won’t do anymore!


Epic Chocolate, Porter & Potato Cake

recipe slightly adapted from: Bibliocook


  • 75 grams dark chocolate – it’s worth using 70% here
  • 225 grams butter, at room temperature
  • 200 grams caster sugar (caster sugar is the same as superfine sugar)
  • 220 grams light brown sugar
  • 4 eggs
  • 75 grams mashed potato (either cook some potatoes and mash them or used leftover mashed potatoes)
  • 250 grams all-purpose flour
  • 25 grams unsweetened cocoa
  • 1 teaspoon baking powder
  • 1/2 teaspoon baking soda
  • 150mls porter – I wish I could have used Eight Degrees Brewing Company’s Knockmealdown Porter, but I used Duclaw Brewing Company’s Sweet Baby Jesus! Chocolate Peanut Butter Porter

For the Cream cheese icing:

  • 200 grams cream cheese
  • 50 grams butter
  • 50 grams confectioners sugar, sifted


Preheat the oven to 350 ° F and line the base of a 9 X 2″ round baking tin.

Melt the chocolate and allow to cool.

Cream the butter and sugars together in a large bowl then add the eggs, one at a time, beating well between each addition.

Mix in the melted chocolate and mashed potato.

Sift the flour, cocoa, baking powder and baking soda together. Gently mix into the cake batter in three additions, alternating with the porter.

Spoon into the prepared tin, leveling the surface with the back of the spoon, and bake for 1 hour – 1 hour, 10 minutes or until the cake feels springy and a toothpick comes out clean from the center.

Cool in the tin for 10 minutes then remove to a cooling rack.

To make the icing, beat the cream cheese and butter together until smooth, then mix in the confectioners sugar. Spread over the cold cake, dusting with a little sweetened cocoa.


5 Responses to Epic Chocolate, Porter & Potato Cake

  1. melissa says:

    Wow, great cake!

  2. I’ve never used potatoes in a cake before!! This is exciting!

  3. Lisa says:

    What an interesting idea to use potatoes in a cake! Chocolate and porter go so well together, I bet this is incredible!

  4. PigLove says:

    oh my – licks piggy lips. That looks delicious! XOXO – Bacon

  5. Oh my! A chocolate peanut butter porter? That would certainly give the cake an extra oomph of flavour.

    Just made myself another cake in advance of St Patrick’s Day, this time using EDB’s Imperial Russian Stout. Looking forward to cutting it…

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