Classic Mocha Slab Cake

This Classic Mocha Slab Cake was my entry to The Great Bloggers Bake-off and Summer Picnic 2020; thank you so much to Caramel, Learner at love, Bereaved Single Dad and A Jeanne in the Kitchen  for hosting this great virtual event!

Viennese style pastries have always been popular in Mexico, and when I was a kid, mocha buttercream torte (pastel vienés de moka) was a classic item to find on the menu at restaurants and tea parlors.  Slices from round or slab mocha cakes were tempting treats to enjoy with a cup of coffee (or a glass of milk in my case).

I have construed my homemade version of this Classic Mocha Slab Cake with two layers of coffee-flavoured chocolate cake, and a rich coffee and cocoa buttercream filling and icing. The cake is finished with chocolate shavings.

Classic Mocha Slab Cake –

Barra de pastel de moka clásica


2 cups all purpose flour
2 cups granulated sugar, plus 2 tbsp for mould
½ cup cocoa powder
1 tsp baking powder
1 tsp baking soda
1 cup milk
½ cup strong coffee, at room temperature
1 tsp vanilla
½ cup vegetable oil, plus 1 tbsp to grease mould
2 eggs

Buttercream Filling and Icing
6 oz (170 g) semi-sweet baker’s chocolate, plus 2 oz (57 g) for shaving
1 cup unsalted butter, at room temperature
3 cups powdered sugar (icing sugar)
6 tbsp whipping cream
2 tbsp instant coffee crystals

Grease a 13X9 inch mould with one tablespoon of oil using a paper towel, then sprinkle to coat with two tablespoons of sugar; set aside.  Preheat oven to 350°F (180°C).  Place dry ingredients (flour, sugar, cocoa powder, baking powder and baking soda) in a large bowl, and mix together with a mixer at low speed, bringing ingredients to the centre of the bowl with a spatula (photo below, left).  In a separate container, mix milk, vanilla and coffee and add to the dry ingredients (photo below, right): 

Pour in vegetable oil (photo below, left), then increase speed to high and mix, scraping down the sides of the bowl with a spatula.  After two minutes, add eggs (photo below right):

Continue mixing at high speed for another two minutes.  Pour batter into prepared mould, and bake in the oven for 40 to 45 minutes, testing with a toothpick, to come out clean after inserting in the centre of the cake.  Remove from the oven and allow to cool down.  

Meanwhile, melt six ounces of the chocolate in a bowl over a pan with boiling water, or put them in a bowl in the microwave oven at high for intervals of twenty seconds, until soft.  Allow to cool down and reserve;   in a separate bowl, dissolve coffee crystals in the cream, and reserve.  Place butter in a large bowl and beat with a mixer at high speed until smooth and fluffy.  Add one cup of powdered sugar; continue mixing until sugar is incorporated, then add melted chocolate:

Mocha Buttercream

Add the rest of the powdered sugar, alternating with the reserved coffee and cream mix.  Continue mixing at high speed, until creamy and uniform. Reserve.

Once the cake has cooled down, slice in half lengthwise, then loosen sides with a spatula. Remove one of the halves onto a flat working surface or tray.  Spread about one cup of mocha buttercream on top.  Remove the other half of the cake and place on top.  Use the rest of the buttercream to cover the top and sides of the layered cake.

Using the last two ounces of chocolate, make shavings using a grater, and sprinkle over the top of the cake:

Serve sections sliced across the slab:

This mouthwatering cake might make one want to give in to temptation and eat it all up, but it is very rich, and a thin slice will be very satisfying.

This was one of the first cakes I ever tasted as a kid, a special treat I once had at a department store’s cafeteria* after shopping all day with my mom.  I was tired, but had been very well behaved, so my mom let me choose a beverage, as well; with such liberating concession, instead of the usual glass of milk, I promptly requested a Coca-Cola™ !   I think my mom had second thoughts about allowing me to pick that time, but complied with a smile, saying that for sure that combination would give me my energy back, just like a “construction worker’s snack” (construction workers were known in Mexico for having a mid-morning snack of Twinkies™ and other packaged pastries along with a bottle of Coca-Cola, for a quick source of energy to keep them going until lunch time.)

When I got myself a slice from my homemade mocha cake, I immediately thought of that happy day with my mom, indulged with a slice of mocha cake and a bottle of Coca-Cola, so of course I had to open a bottle of Coca-Cola (and I just happened to have an old-fashioned glass bottle of Mexican Coca-Cola around, he he):

“El Puerto de Liverpool” in downtown Mexico City (photo from Wikimedia)

* My mom’s favourite department store was “El Puerto de Liverpool” – “The Port of Liverpool”, specifically their oldest store, in downtown Mexico City.   This was the first store of this successful chain, inaugurated in 1936, and named after the actual port in Great Britain, since back then, the company received most of their imported goods sent from there.  The building was a state-of-the-art architectural marvel at the time, and the first store in Mexico to offer escalators.  Their cafeteria was on the mezzanine level when I used to go with my mom.   This store still operates and, although temporarily closed due to the pandemic, the company recently announced the staggered re-opening of their close to 120 stores.

I am sharing my recipe at Over the Moon #234, graciously hosted by Bev @ Eclectic Red Barn, and Marilyn @ Marilyn’s Treats.  UPDATE: Thank you so much to Bev for featuring my cake at this party.

I am also sharing my recipe at Thursday Favourite Things #449 with Bev @ Eclectic Red Barn, Pam @ An Artful Mom, Katherine @ Katherine’s Corner, Amber @ Follow the Yellow Brick Home, Theresa @ Shoestring Elegance and Linda @ Crafts a la Mode.

I am bringing my recipe to Full Plate Thursday #494 with Miz Helen @ Miz Helen’s Country Cottage.

I am joining Fiesta Friday # 338 with Angie @ Fiesta Friday, this week co-hosting with Mollie @ The Frugal Hausfrau.

I am also joining What’s for Dinner? Sunday Link-Up #263 with Helen @ The Lazy Gastronome.

34 thoughts on “Classic Mocha Slab Cake

  1. I like the Mexican Coca Cola in the glass bottles too. AND I’m going to TRY MAKING this cake; sounds and looks good.


  2. That looks delicious! That so funny, as soon as I saw the Coca-Cola bottle scrolling I was thinking, oh boy I love Coca-Cola in a bottle from Mexico, tastes so much better, then I saw you commented on it lol.


  3. ********************************************************
    Thank you for sharing at #OverTheMoon. Pinned and shared. Have a lovely week. I hope to see you at next week’s party too! Please stay safe and healthy. Come party with us at Over The Moon! Catapult your content Over The Moon! @marilyn_lesniak @EclecticRedBarn

    Liked by 1 person

  4. I haven’t really ever heard the word slab cake before but I get it! This looks wonderful…it reminds me, and no insult intended, of a frozen cake I was in love with years ago, by Sarah Lee. They don’t make it any longer and I just loved it!

    I’m looking forward to trying this one! Thanks for sharing at Fiesta Friday this week.



    1. Those rectangular (slab) cakes were popular back then, right?; you could see them at bakeries and supermarkets alike, and yes, I )remember the frozen ones by Sarah Lee, hehe, they were good. Thank you for hosting FF!

      Liked by 1 person

  5. I have a couple questions… okay, a few. I was just, today, looking at ingredients I need. Then I was looking at what pan I would use. Is eleven by nine a typo? Also, have you ever used a round pan for this recipe; perhaps a springform? For a springform or not a springform, would the time and oven temperature be different?


    1. Hi, Marleen; yes, the mould should be 13X9 inches, thank you! I have corrected the post and the printable recipe. For any pan, it is the same temperature, and for round pans, I would recommend using two, either 8 or 9 inches in diameter, and they may be springform or not; these should take around 40 minutes, but check at 35 just in case, depends a lot on each particular oven and pan diameter.


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