Revisited: Mint Layer Cake with White Chocolate Mint Ganache Filling and Chocolate Fudge Icing

My dear, dear friend just had a baby. Another friend and I took dinner to her last night. My assignment was dessert. I remembered my friend telling me that she really wanted me to make her a Mint Layer Cake for her birthday. I thought, "Why not make one now?"

When it has been awhile since I've made a certain recipe, I like to go back and revisit the process and ingredients, especially if I've learned a few new tricks.

So, I went back and looked at the recipe. I knew I would follow the recipe for the cake because it is absolutely fool-proof. But, I was remembering that the white chocolate mint ganache filling was a little more finicky...and I was correct.

I didn't end up having enough cream or bittersweet chocolate on hand to make the whipped chocolate ganache for the icing, so I made a rich, chocolate fudge icing instead. (The cake and chocolate fudge icing recipes can be found below.)

I wanted to document the making of the ganache and add some helpful tips. I discovered that there are many ways to mess up this ganache filling and ways to remedy it.

Mint Layer Cake with White Chocolate Mint Ganache Filling and Chocolate Fudge Icing
cake recipe from Hershey's, filling adapted from Epicurious.com, fudge icing is an original recipe

Ingredients:

For Chocolate Cake:
2 cups white sugar
1 3/4 cups all-purpose flour
3/4 cup Hershey's cocoa
2 tsp. baking soda
1 tsp. baking powder
1 tsp. salt
2 tsp. vanilla extract
2 eggs
1 cup buttermilk
1 cup very hot water
1/2 cup vegetable oil

For White Chocolate Mint Ganache Filling:
3/4 lb. (12 oz.) good quality white chocolate (such as Ghirardelli or Lindt)
1/2 cup heavy cream
1 tbsp. butter
1 tsp. pure peppermint extract
1 tsp. creme de menthe extract
2-3 drops of green food coloring

For Chocolate Fudge Icing:
1 1/2 sticks salted butter (use unsalted if you like it better)
1-2 oz. bittersweet chocolate
3/4 cup cocoa powder
4-4 1/2 cups powdered sugar
a little milk

Instructions:

For cake:
Heat oven to 350 degrees. Prepare 2, 9" round cake pans by greasing well and lining the bottom with a 9" round piece of wax paper, and greasing the wax paper.

Sift all the dry ingredients into a large mixing bowl. Whisk together the buttermilk, eggs, oil, and vanilla extract. Beat with an electric mixer on medium speed for 2 minutes. Slowly add the cup of hot water while mixing on low speed. The batter will be thin.

Using a 1-cup measuring cup, evenly distribute the cake batter between the 2 pans--each one gets about 3 cups of batter. Bake the cakes at 350 degrees for about 30-35 minutes, or until a toothpick inserted into the center comes out clean. Let cool in pans for about 5-10 minutes. Then remove to a wire rack to cool completely. Place in fridge or freezer until ready to frost the cake--this will make it easier to frost and there will be less loose crumbs.

For White Chocolate Mint Filling:
Chop the white chocolate into small chunks and place in a medium sized bowl.

Place the bowl over a pot of simmering water--making sure the bowl is big enough that it doesn't touch the water (a.ka. a double boiler) . Add the cream and butter. Stir occasionally until the chocolate and butter melt. Remove bowl from heat. Add the extracts and food coloring directly to the bowl--leave out the water. It can cause the chocolate to seize. Cover with plastic wrap and refrigerate until the ganache thickens. Make sure it doesn't get too thick, or you won't be able to whip it, or spread it very well.  If you want to, you can whip the ganache on medium speed with an electric mixer. It may get quite a bit thicker--too thick to spread. Just place it in the microwave for a few seconds to soften it to spreading consistency. Spread between the two cake layers and return the cake to the fridge to set up. Then frost with the chocolate icing. I still agree with the directions above. A few extra seconds of beating can make the difference between a spreadable whipped ganache and one that is too hard and "crumbles". It's sort of like when you make a classic French or Swiss Meringue Buttercream and need to control the temperature to get the right consistency.

For Fudge Icing:

Place the butter and bittersweet chocolate in a large, microwave-safe bowl. Microwave on 50% power for 2 minutes, stir well to remove any lumps of butter or chocolate.

Add the cocoa powder and mix well. Using an electric mixer, beat in the powdered sugar a little at a time, alternating with a little milk until the icing has reached a spreadable consistency. (Sometimes it needs a few minutes in the fridge to firm up.)

Use as needed. This recipe will yield enough icing for one 8 to 9-inch, four layer cake.

To finish the cake:This time, I split the two chocolate cake layers in half so I ended up with 4 layers of cake, 2 layers of chocolate fudge icing (top and bottom), and a middle layer of thick whipped ganache. From top to bottom, the entire cake was frosted with the remaining chocolate fudge icing.

How-To Pictures and Instructions:

Chop the white chocolate into small chunks and place in a medium sized bowl.




Place the bowl over a pot of simmering water--making sure the bowl is big enough that it doesn't touch the water (a.k.a. a double boiler) . Add the cream and butter. Stir occasionally until the chocolate and butter melt. Remove bowl from heat.





Add the extracts and food coloring directly to the bowl.



Cover with plastic wrap and refrigerate until the ganache thickens. Make sure it doesn't get too thick, or you won't be able to whip it, or spread it very well. 



If you want to, you can whip the ganache on medium speed with an electric mixer. It may get quite a bit thicker--too thick to spread. Just place it in the microwave for a few seconds to soften it to spreading consistency. Spread between the two cake layers and return the cake to the fridge to set up. Then frost with the chocolate icing.

A few extra seconds of beating can make the difference between a spreadable whipped ganache and one that is too hard and "crumbles". It's sort of like when you make a classic French or Swiss Meringue Buttercream and need to control the temperature to get the right consistency.

Troubleshooting:

I made the mistake of overbeating the cooled ganache. I had forgotten that I could rewarm the ganache in the microwave, so instead I tried adding a few tablespoons of heavy cream. BIG MISTAKE. I added a few tablespoons of butter. Another BIG MISTAKE. Rewarming is really the only way to remedy overbeating.

I had to warm the ganache twice after overbeating it! The extra cream and butter didn't make that much of a difference, but I learned my lesson and next time will follow the recipe.

For a quick chill, you can place the bowl in the freezer for about 5-10 minutes.



I placed the remaining mint ganache in a piping bag and made little peaks of ganache on top of the cake. Since I didn't have any Andes mints on hand, I shaved some bittersweet chocolate with a vegetable peeler and sprinkled it over the top. The effect was very similar to my Chocolate Peanut Butter Mousse Cake. (They looked almost identical in appearance.)


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