Dark Chocolate Cake with Roasted Chestnut Buttercream

OH MY WORD this cake is GOOD!  I saw some fresh chestnuts at the grocery store, snagged the little treats (they only seem to pop up around the holidays), and decided to turn them into a roasted chestnut buttercream.  Then I picked up my handy dandy Flavor Bible for pairing ideas and decided a chocolate base would go beautifully with the earthy flavors of the roasted chestnuts.  And for those of you who say you don’t like cake, I dare you to give it a try.  Grocery store cakes do the world a disservice by making yucky cakes with “buttercreams” consisting of not much more than partially hydrogenated oil.  That’s not buttercream.  Homemade is definitely the way to go, and it’s not difficult, and SO worth the results.   This cake is so perfect for the holidays!

Dark Chocolate Cake: This is the best chocolate cake I have EVER had.  If I didn’t make it, I would think this was an oil based cake because it is so darned moist.  Never ever have I had a butter cake this moist, it’s amazing.  It was my first time trying it yesterday, and this will be my go-to chocolate cake from now on.  What’s really awesome is it’s made from a hot chocolate base, so the chocolate flavor is really there.  I also added some mini chocolate chips to the batter right at the end, and they melted slightly in the oven, giving the cake these gooey chocolate “hot spots.”  Yum.  This will give you 3-9 inch rounds of cake.

2 cups boiling water
1 cup unsweetened cocoa powder
2.75 cups all purpose flour
2 tsp baking soda
1/2 tsp baking powder
1/2 tsp sea salt
1 cup butter, softened
2.25 cups white sugar
4 extra large eggs, lightly whisked
1.5 tsp vanilla extract
1 cup mini chocolate chips

Preheat your oven to 350 degrees F.  Butter and flour your cake pans (I like to rub the leftover butter wrappers in the cake pan for easy and resourceful application.  You wouldn’t want to waste any of that butter, would you?)

In a big bowl, pour the boiling water over the cocoa powder, and whisk until smooth (it’s essentially a big bowl of unsweetened hot chocolate.  Don’t drink it though…it’s pretty bitter).

Place your hot cocoa into an ice bath so it can cool.  Next, sift together the flour, baking soda, baking powder, and salt, and set it aside for later.

Now, remember all the things I taught you about creaming yesterday?  Time to put them to work!  The original recipe for this cake says “cream butter and sugar together until light and fluffy,” which as I noted yesterday, isn’t very helpful.  If you didn’t read my creaming post, take a look so you know how to properly cream.  Place the butter in a stand mixer fitted with the paddle attachment, mix on low for 1 minute, then with the mixer turned up to medium, slowly add in the sugar.  Slowly pour in the eggs with the mixer on low, add the vanilla, and continue mixing until absorbed.

Add one third of the dry ingredients and cooled hot chocolate liquid at a time, alternating between the two, starting with the dry and finishing with the hot chocolate liquid.  Stir in your mini chocolate chips at the end. 
Pour the batter evenly into the prepared cake pans and bake for 25 minutes, until a toothpick inserted into the center comes out clean.  Remove from the oven and let the cakes cool.

Roasted Chestnut Buttercream: This is a professional style buttercream (don’t let that scare you, it just means it’s good quality stuff).  A lot of people make a buttercream that consists only of butter beaten with powdered sugar.  Many people don’t notice, but it has a gritty consistency from the cornstarch in the powdered sugar that I really don’t like, and while it is easy, I don’t find it to be very good.  Professional style buttercreams aren’t too difficult, so I highly suggest you give it a try…it’s a million times better…plus, it uses less butter =)

3/4 pound chestnuts
2 cups sugar
2/3 cup water
8 egg yolks, warmed (before separating the egg yolks and whites, place the eggs in a bowl of hot water for 5 minutes)
1.5 cups butter, diced into small cubes
1.5 tsp vanilla

Preheat your oven to 425 degrees F.  If your chestnuts are dirty, wipe them off with a damp paper towel.  Get a sharp knife, and cut X’s into the chestnuts like this:

If you don’t cut X’s into the chestnuts, they can explode (even after they have cooled), so it’s important to let the steam escape.  Plus, it will make the peeling a lot easier!  Roast the chestnuts in the oven for about 20-25 minutes on a sheet pan.  They should come out looking like this when they’re done:

Peel both the shell and inner skin off the chestnuts, and open them up so you can see into the middle of the chestnut (it is very common for a few of them to be spoiled in the middle).  Discard the spoiled ones.  Place your chestnuts in a food processor, add the vanilla, and grind them up as finely as you can.  You won’t be able to grind them into a paste with the food processor, but you should be able to turn it into a powder.  Set the ground chestnuts aside for later.

In a stand mixer fitted with the whisk attachment, beat the egg yolks on high speed for 8 minutes until they are very pale.  In the meantime, combine the sugar and water in a heavy bottomed saucepan over medium heat, and let the sugar syrup simmer toward the soft ball stage (238 degrees on an instant read thermometer).  When both the egg yolks and the sugar syrup are ready, pour the sugar syrup into the mixing bowl (the mixer should still be on high speed), aiming as best as you can to pour between the wire whisk and the side of the bowl.  Notice that the mixing bowl is very hot to the touch.  Beat the egg yolk sugar mixture until the bowl feels neither hot nor cold (it took me about 5 minutes).

Look like how glossy and tasty that looks!  Turn the mixer down to medium and add the butter, a couple cubes at a time, to the bowl.  Wait until each installment of butter is absorbed until you add the next batch.  You want to beat the buttercream for 10 minutes, so it can get nice and fluffy.  Fold the chestnut mixture in, spread your buttercream onto the cooled cakes, and enjoy!

My next post will be on Monday January 10th (I am going out of town for two weeks).  Happy holidays!  If you would like to receive email updates when I make new posts, you can do that in the little box in the upper right corner of my homepage.  Thanks for reading!

Roasted chestnut buttercream adapted from James Peterson’s Professional-Style Buttercream recipe in his book Baking.  Chocolate Cake recipe adapted from Carol’s Dark Chocolate Cake.  Many thanks to both.

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8 Responses to Dark Chocolate Cake with Roasted Chestnut Buttercream

  1. I’ve seen chestnuts at the grocery store before but have never bought any because I had no clue what to do with them. I may just have to buy some and try this! Thanks for all the info on preparing chestnuts as well!

  2. My first thought when I saw the picture was Oh Wow! That is one amazing cake!

  3. Judy says:

    When do you add the chestnuts? I read the directions three times and don’t see anything about adding the chestnuts to the frosting.

    • Joanne says:

      Hi Judy, Thanks for pointing this out. I can’t believe I left that out! I folded them in at the end, so we don’t interfere with the eggs building up their volume.

  4. lacylola says:

    Egg yolks? I’ve never seen anything but egg whites be used in buttercream frostings; in fact the pictures you show look like beaten egg whites!

    • Joanne says:

      Really? I’ve seen egg yolks more commonly than egg whites, except in meringue type frostings where you use egg whites to build volume. The egg yolks here add more body and a nice mouthfeel (I mean, that’s where the fat is). It’s definitely egg yolks for this one =)

  5. R says:

    What’s the approximate serving size?

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