Sunday, October 19, 2014

Mocha Buttercream Cake with Hazelnut Buttercrunch

(8 inch cake; about 9 servings)

A few weeks ago I rented a small furnished studio apartment near Sequim, WA. It has a tiny kitchen area, but it's big enough to cook most things.

Over a two day period this past week, I baked and assembled a mocha buttercream cake with hazelnut buttercrunch in (what for me was) a limited kitchen. In Dallas I had a large powerful kitchen machine at my disposal and without it I felt a bit unprepared for this task. I ended up mixing the batter for this cake by hand and used a small handheld 200 watt beater for the buttercream. I really wanted to try an Italian buttercream for this but made a German version instead because that required less beating. I will try the Italian buttercream at some point, but it was my mum's birthday this weekend and I didn't want to take any chances.

For the cake itself, I adapted a recipe from Hershey's. This is a type of devil's food which turned out perfect. The finished moist cake had a nice even texture. I didn't sweeten the buttercream very much because I figured the amount of sugar in the cake batter (more than I usually add), plus the hazelnut buttercrunch would balance things out in terms of sweetness. You might consider adding more sugar to the buttercream if you are making it for something else.

adapted Black Magic Cake Recipe from Hershey's
1 cup unbleached all purpose flour
1 cup sugar
1 tsp baking soda
1/2 tsp baking powder
1/4 tsp salt
1/2 cup hot strong espresso or black coffee
1/3 cup cocoa
1/2 cup milk
1 tsp lemon juice or vinegar
1/3 cup canola oil
2 small eggs or 1 extra large egg
1 1/2 tsp vanilla extract

Preheat oven to 350°F.

Grease an 8 inch square pan (all I had) or an 8 inch round pan (what I would have preferred to use). Line the greased pan with parchment paper and lightly grease that as well. Set aside.

Stir together flour, sugar, cocoa, baking soda, baking powder and salt in large bowl. Set aside

Stir together the hot coffee and cocoa until smooth and pour that into a second bowl. Stir together the milk and lemon juice or vinegar. When the milk begins to curdle, add that to the coffee and chocolate mixture. Stir in the oil. Add the 2 small eggs or 1 extra large egg (I have been buying eggs from a local farmer, selecting only the small ones because they are so cute) and whisk until everything is well combined.

Pour the wet mixture into the dry ingredients and whisk for about 30 seconds. Pour the batter into the prepared pan and place into the middle of the preheated oven.

Bake for about 30-35 minutes or until a toothpick inserted into the center of the cake comes out clean. Remove the cake from the oven and allow to cool in the pan.

German Mocha Buttercream
2 cups milk
1/4 cup corn starch
2 - 5 tbsp sugar
2 tbsp instant coffee
pinch of salt
2/3 cup semisweet chocolate chips
about 1 cup butter, (2 sticks) at room temperature

German buttercream is made by beating butter into cooled pudding. The proportions are usually about 2 parts pudding to one part butter. The pudding should be slightly sweeter and more flavorful to compensate for the plain butter. What's really important here is that both pudding and butter be the same temperature, otherwise the mixture might curdle and not come together. I find it easiest to prepare the pudding the night before and leave the butter out on the counter along with the pudding.

Place 1 1/2 cups milk into a small saucepan set over medium-low heat. Stir together the remaining 1/2 cup milk with the corn starch until smooth and set aside. Stir in the amount of sugar you are using. I added 2 tablespoons, but if you like your buttercream sweeter, then add more sugar. Stir until the sugar has dissolved.

When the mixture begins to bubble slightly at the sides,  stir in the instant coffee and the chocolate chips. Stir until the chocolate has completely melted.

Add the reserved milk and corn starch mixture. Increase the heat slightly and stir until the pudding begins to thicken. Continue to stir until you notice the pudding begin to bubble, then remove the pan from the heat.

Cover the surface of the pudding with plastic wrap to prevent a skin from forming and allow the pudding to cool completely; preferably overnight. 

Place the cooled pudding into a bowl. Beat in the butter, a tablespoon or two at a time. Initially the mixture will be streaky and curdled looking, but eventually the buttercream will come together. You will notice the buttercream all of a sudden "stiffen" as you are beating in the butter. You can stop at this point, even if you haven't used all of the butter.

If for some reason the buttercream has curdled, you can save the buttercream by either immersing the bottom of the bowl in hot water momentarily to gently heat the mixture, or by placing the entire bowl into the microwave (if it's microwave safe) for 10-20 seconds at a time. Beat the mixture at high speed until the buttercream emulsifies. You might have to cool it a bit afterwards (then beat it again) before spreading it over the cake.

hazelnut buttercrunch (this recipe makes a bit extra)
1 cup sugar
2 tbsp agave nectar or corn syrup
1/4 cup butter, (1/2 stick) 
1 1/2 cups toasted hazelnuts

I usually make this without a candy thermometer by watching the color of the sugar mixture. It might be easier to use white sugar and corn syrup if you haven't done this before.

Prepare a cookie sheet by either greasing it or lining it with parchment paper or a silicone mat. Set aside.

Combine the sugar, agave nectar or corn syrup and butter in a small non stick sauce pan and place over medium heat. Cook and stir the mixture until the butter has completely combined with the sugar and the color is a nice rich medium brown.

Add the hazelnuts and cook for another 30 seconds or so while stirring all the while. Pour the mixture onto the prepared cookie sheet and using a wooden spoon push the nuts until they are in a single even layer. You will have to work quickly as the mixture will begin to harden quickly as it cools.

When the buttercrunch has cooled completely, roughly chop the mixture with a large sharp knife. Set aside.

Rum syrup
1 tbsp apple, pomegranate or red currant jelly
1/4 cup rum

Combine the jelly with half of the rum in a microwave proof container and heat for about 30-45 seconds or until the jelly has melted. Stir in the remainder of the rum and set aside.

To assemble the cake.
Remove the cake from the pan and peel away the parchment paper. Carefully slit the cake into two layers horizontally. Remove the top layer and set aside.

Place the bottom layer (cut side up) onto a serving plate and place strips of parchment paper (about 4 inches wide) underneath the sides of the cake, allowing for about 2 1/2 inches of the strips to extend beyond the edges.

Spread the rum syrup evenly over the top of the bottom layer. Spread about 1/3 of the mocha buttercream over that. Sprinkle about 3/4 - 1 cup of chopped hazelnut buttercrunch evenly over the buttercream.

Place the top layer of the cake over the bottom layer and spread another 1/3 of the buttercream over the top.

Spread the remaining buttercream (reservng a small amount for decorating the top if desired) onto the sides of the cake. Carefully press the chopped hazelnut mixture onto the sides of the cake using the parchment paper stripes to help with any stray bits.

There's plenty of hazelnut buttercrunch, so you can cover the entire top of the cake with it, or use a few pieces to decorate and eat the rest. :)

Carefully remove the strips of parchment paper before serving.

1 comment:

Sippity Sup said...

I've never tried the floss trick on a square cake. Gl;ad to know it's not just for round. GREG

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