The Daring Bakers: Hazelnut Gateau with Praline Buttercream

Ooooh the Daring Bakers challenge this month was right up my alley! I love all things cake (with extra frosting, please) and hazelnut-chocolate is one of my favorite flavor combinations. So I was really excited to see that our challenge was to make a hazelnut layer cake with praline buttercream.

The cake part turned out gorgeous--the recipe called for LOTS of ground hazelnuts, and then a touch of lemon zest, which I thought was a really nice addition--the citrus flavor cut some of the richness of the nuts and was subtle but present. The texture was perfect, and it stayed moist for days in the fridge. I will definitely be making this cake again!

The buttercream was a whole different story. The recipe called for homemade praline (caramelized sugar and nuts, ground into a paste) in a Swiss meringue buttercream. Perhaps I was a bit cocky, but I eschewed the Swiss meringue for my tried-and-true Italian meringue buttercream recipe, and instead of making homemade praline I used some I had in a can from Love n' Bake. (It was fabulous, by the way. Such a great flavor!) However, my carefree off-recipe experiments, combined with stupendous heat in my kitchen, yielded a very, very soft buttercream that barely held up. It was practically melting, it was so pathetic. So the assembly of this cake was frustrating, to say the least, because my cake wouldn't hold its shape and none of my piping lasted more than a minute or two.


However, the final product still turned out pretty fantastic. The hazelnut cake is filled with a mix of praline buttercream and whipped cream. I made cocoa whipped cream to boost the chocolate flavor, and used very dark chocolate in the ganache glaze. The result was a nutty cake, oozing with soft fillings, bursting with toasted nut and dark chocolate flavor. I topped it all off with some chopped toasted hazelnuts and dark chocolate triangles. It's a little embarrassing to admit, but my husband and I ate the whole thing. In three days! We are powerless in the face of desserts. And also, we are pigs.
You can find the whole recipe after the jump.

Here's the original recipe, slightly abridged. In addition to my buttercream variations and cocoa additions, I also omitted the apricot glaze (seemed weird for a nut-chocolate cake) and added an outside layer of buttercream to help my chocolate glaze set up.

Filbert (Hazelnut) Gateau
1 ½ cups hazelnuts, toasted/skinned
2/3 cup cake flour, unsifted
2 Tbsp. cornstarch
7 large egg yolks
1 cup sugar, divided ¼ & ¾ cups
1 tsp. vanilla extract
½ tsp. grated lemon rind
5 lg. egg whites
¼ cup warm, clarified butter (100 – 110 degrees)

Position rack in the lower 3rd of the oven and preheat to 350 degrees. Grease and flour a 10” X 2” inch round cake pan.

Using a food processor, process nuts, cake flour, and cornstarch for about 30 seconds. Then, pulse the mixture about 10 times to get a fine, powdery mixture. You’ll know the nuts are ready when they begin to gather together around the sides of the bowl. While you want to make sure there aren’t any large pieces, don’t over-process. Set aside.

Put the yolks in the bowl of an electric mixer, with the whisk attachment, and beat until thick and light in color, about 3-4 minutes on med-high speed. Slowly, add ¾ cup of sugar. It is best to do so by adding a tablespoon at a time, taking about 3 minutes for this step. When finished, the mixture should be ribbony. Blend in the vanilla and grated lemon rind. Remove and set aside.

Place egg whites in a large, clean bowl of the electric mixer with the whisk attachment and beat on medium speed, until soft peaks. Increase to med-high speed and slowly add the remaining ¼ cup of sugar, over 15-20 seconds or so. Continue to beat for another ½ minute.
Add the yolk mixture to the whites and whisk for 1 minute.

Pour the warm butter in a liquid measure cup (or a spouted container). * It must be a deep bottom bowl and work must be fast.* Put the nut meal in a mesh strainer (or use your hand – working quickly) and sprinkle it in about 2 tablespoons at a time – folding it carefully for about 40 folds. Be sure to exclude any large chunks/pieces of nuts. Again, work quickly and carefully as to not deflate the mixture. When all but about 2 Tbsp. of nut meal remain, quickly and steadily pour the warm butter over the batter. Then, with the remaining nut meal, fold the batter to incorporate, about 13 or so folds.

With a rubber spatula, transfer the batter into the prepared pan, smoothing the surface with the spatula or back of a spoon. **If collected butter remains at the bottom of the bowl, do not add it to the batter! It will impede the cake rising while baking.

Tap the pan on the counter to remove air bubbles and bake in the preheated oven for 30-35 minutes. You’ll know the cake is done when it is springy to the touch and it separates itself from the side of the pan. Remove from oven and allow to stand for 5 minutes. Invert onto a cake rack sprayed with nonstick coating, removing the pan. Cool the cake completely.

*If not using the cake right away, wrap thoroughly in plastic wrap, then in a plastic bag, then in the refrigerator for up to 3 days. If freezing, wrap in foil, then the bag and use within 2-3 months.

Sugar Syrup
Makes 1 cup, good for one 10-inch cake – split into 3 layers

1 cup water
¼ cup sugar
2 Tbsp. dark rum or orange flavored liqueur

In a small, yet heavy saucepan, bring the water and sugar to a boil and simmer for 5 minutes. Remove from heat, add the liqueur. Cool slightly before using on the cake. *Can be made in advance.

Praline Buttercream
1 recipe Swiss Buttercream
1/3 cup praline paste
1 ½ - 2 Tbsp. Jamaican rum (optional)

Blend ½ cup buttercream into the paste, then add to the remaining buttercream. Whip briefly on med-low speed to combine. Blend in rum.

Swiss Buttercream
4 lg. egg whites
¾ cup sugar
1 ½ cups (3 sticks) unsalted butter, slightly firm
1 ½ -2 Tbsp. Grand Marnier or liqueur of your choice
1 tsp. vanilla

Place the egg whites in a lg/ bowl of a elevtric mixer and beat with the whisk attachment until the whites are foamy and they begin to thicken (just before the soft peak stage). Set the bowl over a saucepan filled with about 2 inches of simmering water, making sure the bowl is not touching the water. Then, whisk in the sugar by adding 1-2 tablespoon of sugar at a time over a minutes time. Continue beating 2-3 minutes or until the whites are warm (about 120 degrees) and the sugar is dissolved. The mixture should look thick and like whipped marshmallows.
Remove from pan and with either the paddle or whisk attachment, beat the egg whites and sugar on med-high until its a thick, cool meringue – about 5-7 minutes. *Do not overbeat*. Set aside.

Place the butter in a separate clean mixing bowl and, using the paddle attachment, cream the butter at medium speed for 40-60 seconds, or until smooth and creamy. *Do not overbeat or the butter will become toooooo soft.*

On med-low speed, blend the meringue into the butter, about 1-2 Tbsp. at a time, over 1 minute. Add the liqueur and vanilla and mix for 30-45 seconds longer, until thick and creamy.

Refrigerate 10-15 minutes before using.

Refrigerate in an airtight container for up to 5 days, or can be frozen for up to 6 months. If freezing, store in 2 16-oz. plastic containers and thaw in the refrigerator overnight or at room temperature for several hours.

Praline Paste
1 cup (4 ½ oz.) Hazelnuts, toasted/skinless
2/3 cup Sugar
Line a jelly roll pan with parchment and lightly butter.

Put the sugar in a heavy 10-inch skillet. Heat on low flame for about 10-20 min until the sugar melts around the edges. Do not stir the sugar. Swirl the pan if necessary to prevent the melted sugar from burning. Brush the sides of the pan with water to remove sugar crystals. If the sugar in the center does not melt, stir briefly. When the sugar is completely melted and caramel in color, remove from heat. Stir in the nuts with a wooden spoon and separate the clusters. Return to low heat and stir to coat the nuts on all sides. Cook until the mixture starts to bubble. **Remember – extremely hot mixture.** Then onto the parchment lined sheet and spread as evenly as possible. As it cools, it will harden into brittle. Break the candied nuts into pieces and place them in the food processor. Pulse into a medium-fine crunch or process until the brittle turns into a powder. To make paste, process for several minutes. Store in an airtight container and store in a cook dry place. Do not refrigerate.
Ganache Glaze
Makes about 1 cup, enough to cover the top and sides of a 9 or 10 inch layer or tube cake

6 oz. (good) semisweet or bittersweet chocolate, like Lindt
6 oz. (¾ cup heavy cream
1 tbsp. light corn syrup
1 Tbsp. Grand Marnier, Cointreay, or dark Jamaican rum (optional)
¾ tsp. vanilla
½ - 1 tsp. hot water, if needed

Blend vanilla and liqueur/rum together and set aside.

Break the chocolate into 1-inch pieces and place in the basket of a food processor and pulse until finely chopped. Transfer into a medium sized bowl and set aside.

Heat the cream and corn syrup in a saucepan, on low, until it reached a gentle boil. Once to the gently boil, immediately and carefully pour over the chocolate. Leave it alone for one minute, then slowly stir and mix the chocolate and cream together until the chocolate is melted and incorporated into the cream. Carefully blend in vanilla mixture. If the surface seems oily, add ½ - 1 tsp hot water. The glaze will thicken, but should still be pourable. If it doesn’t thicken, refrigerate for about 5 minutes, but make sure it doesn’t get too cold!

Assembling Cake

Cut a cardboard disk slightly smaller than the cake. Divide the cake into 3 layers and place the first layer top-side down on the disk. Using a pastry brush, moisten the layer with 3-4 Tbsp. of warm sugar syrup. Measure out 1 cup of praline buttercream and set aside.

Spread the bottom layer with a ¼-inch thickness of the remaining buttercream. Cover with ½ of the whipped cream, leaving ¼-inch border around the edge of the cake. Place the middle layer over the first, brush with sugar syrup, spreading with buttercream. Cover with the remaining whipped cream.

Moisten the cut side of the third layer with additional sugar syrup and place cut side down on the cake. Gently, press the sides of the cake to align the layers. Refrigerate to chill for at least 30 minutes.

Lift the cake by sliding your palm under the cardboard. Holding a serrated or very sharp night with an 8-ich blade held parallel to the sides of the cake, trim the sides so that they are perfectly straight. Cut a slight bevel at the top to help the glaze drip over the edge. Brush the top and sides of the cake with warm apricot glaze, sealing the cut areas completely. Chill while you prepare the ganache.

Place a rack over a large shallow pan to catch the ganache drippings. Remove the gateau from the refrigerator and put it the rack. With a metal spatula in hand, and holding the saucepan about 10 inches above the cake, pour the ganache onto the cake’s center. Move the spatula over the top of the ganache about 4 times to get a smooth and mirror-like appearance. The ganache should cover the top and run down the sides of the cake. When the ganache has been poured and is coating the cake, lift one side of the rack and bang it once on the counter to help spread the ganache evenly and break any air bubbles. (Work fast before setting starts.) Patch any bare spots on the sides with a smaller spatula, but do not touch the top after the “bang”. Let the cake stand at least 15 minutes to set after glazing.