Marjolaine

French buttercream, made using egg yolks, is the ultimate in decadence. It can be a little tricky because of the high fat content and can split when adding the butter. Go slow and make sure your butter is not overly soft for a perfect result. The addition of praline powder gives the buttercream a nutty toastiness that will keep you going back for more.

Ingredients

Dacquoise:

• 1 cup finely ground toasted almonds
• 1 cup finely ground toasted hazelnuts
• 1 ¼ cup granulated sugar, divided
• 2 tbsp flour
• ½ tsp salt
• 6 egg whites

Ganache:

• 1 cup dark chocolate callets
• 1 cup 35% cream
• 2 tbsp white corn syrup

Praline powder:

• 1 cup granulated sugar
• ¼ cup water
• 1 cup slivered almonds, toasted

French Buttercream:

• 1 cup granulated sugar
• ¼ cup water
• 6 egg yolks
• ¼ tsp fine salt
• 1 cup butter, softened
• 1 tsp vanilla

Decoration:

• 2 cups slivered almonds, toasted
• 7 whole toasted hazelnuts

Preparation

Heat oven to 300F degrees. Spray and line two 12x8-inch rimmed baking sheets (¼ sheet pans) with parchment to overhang the two long sides. Line another rimmed sheet with parchment. Set aside. 

Dacquoise: 

Stir together the nuts, ½ cup sugar, flour and salt in a small bowl. 

In the bowl of a stand mixer fitted with a whisk attachment, whisk egg whites until soft peaks. Add the remaining ¾ cup sugar, one tablespoon at a time, until glossy and stiff. Gently fold in the nut mixture and spread evenly into the two prepared pans with overhanging parchment. Bake until lightly golden and firm, about 1 hour. Turn the oven off and prop the oven door open with a wooden spoon to cool completely. Turn out carefully from pan and remove parchment. Using a serrated knife, gently cut each piece in half lengthwise to create four 12 x 4-inch pieces.  

Ganache: 

Place the chocolate in a medium heat-proof bowl. Bring cream just to a boil in a small saucepan and pour over chocolate. Let sit for 2 minutes before stirring until smooth. Stir in the corn syrup. Pour onto a rimmed baking sheet and set aside to cool until spreadable but firm. 

Praline powder: 

Combine the sugar and water into a small saucepan. Bring to a boil over medium-high heat. Reduce the heat to medium and boil until a candy thermometer reads 345F degrees, brushing the sides of the pan with a damp pastry brush if sugar appears on sides of pan to prevent crystallization. Immediately stir in the almonds; pour the mixture onto the remaining prepared baking sheet. Spread a thin layer to cool. Once hard, remove from the parchment and break into pieces. Place into the bowl of a food processor and pulse until fine powder. 

Buttercream: 

Combine the sugar and water into a small saucepan. Bring to a boil over medium-high heat. Reduce heat to medium and boil until a candy thermometer reads 238F degrees, brushing the sides of the pan with a damp pastry brush if sugar appears on sides of pan to prevent crystallization. Allow bubbling to subside.   

Meanwhile, place the egg yolk in the bowl of a stand mixer fitted with a whisk attachment. Gradually stream in the sugar syrup with the mixer running on medium. Increase speed to medium-high and continue to whip until cooled to room temperature, about 4 to 6 minutes. Add salt. 

With the mixer running on high, slowly add the butter, one tablespoon at a time, whisking between additions to incorporate until smooth and fluffy. Add vanilla and continue to whisk for 1 minute.  

Stir the praline powder into the remaining buttercream. 

For assembly: 

Place a dollop of ganache on centre of serving platter and adhere 1 piece of dacquoise rectangle in centre of platter. Spread evenly with ¼ of buttercream and top with another dacquoise. Spread evenly with ½ of the ganache and top with a dacquoise layer. Spread with another ¼ of buttercream and a final dacquoise layer. Mask cake with the remaining buttercream and decorate sides with almonds. Spoon the remaining ganache into a piping bag fitted with a small round tip and pipe kiss-shaped dollops along top edge of cake. Pipe 7 small dollops of buttercream evenly spaced lengthwise down the centre of the cake. Press hazelnuts lightly into the buttercream dollops. 

Yield: Makes 1 cake