Marjolane Cake with Almonds and Hazelnuts (French Gâteau Marjolaine)

This lovely French cake has just three components and is baked entirely on a cookie sheet. The original recipe is adapted from the cookbook Ma Gastronomie by marjolaine's inventor Fernand Point. A type of dacquoise, with its nut meringue layers filled with three different rich creams, this dessert is truly a masterpiece by the father of the modern French cuisine. This spectacular dessert is chocolaty, nutty, crunchy and creamy. Even though there are lots of steps to this recipe, you can spread the work over several days and the cake can be assembled a day before. So, take your time, enjoy the process, and get ready to take a bow. 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.

Dacquoise:
1 cup almonds, toasted and finely ground
1 cup hazelnuts, toasted and finely ground
1¼ cup granulated sugar, divided
2 Tbsp. all-purpose flour, unbleached
½ tsp. sea 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 sea salt
1 cup butter, softened
1 tsp. pure vanilla extract

Decoration:
2 cups slivered almonds, toasted
7 whole toasted hazelnuts

Preheat oven to 300°F (150°C/130°C fan, Gas Mark 2). Spray and line two 12x8" rimmed baking sheets (¼ sheet pans) with parchment to overhang the two long sides. Line another rimmed sheet with parchment. Set aside.

For the 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 12x4" pieces.

For the 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.

For the 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 345°F 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.

For the 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 238°F 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 4-6 minutes. Add salt.

With the mixer running on high, slowly add the butter, one Tbsp. 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.

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.

Makes 1 cake.