White Chocolate Mousse Cake with Frangelico Cream and Hazelnut Praline

Grease a baking sheet or line it with a silicone mat. Combine the sugar, syrup, and water in a heavy saucepan over medium-low heat and heat until the sugar is completely dissolved; do not stir. Increase the heat to medium and cook until the sugar has turned a golden brown (hard-crack stage; about 300 F on a candy thermometer.) Remove from heat and stir in the nuts and butter until the butter has completely melted and the hazelnuts are coated. Pour onto the prepared pan and spread out with a spatula. Let cool. Break into pieces. Keeps up to 2 weeks in a airtight container.

To make the praline: Cover a work surface with waxed paper. Bring the water and sugar to a boil over medium-high heat. Continue boiling without stirring until it turns a medium brown color, 238 F on a candy thermometer. Remove from heat and stir in the hazelnuts. Spread the praline over the waxed paper and let cool. Break into small pieces, then grind to small bits in a food processor.

To make the cake: Preheat the oven to 350 F. Butter one 9-inch layer pan. Line the bottom of the pan with parchment paper and butter the paper. Flour the pan and paper; tap out excess flour.

Melt the chocolate in a double boiler over barely simmering water. Stir until smooth. Remove from heat; cool to room temperature.

Sift flour and baking powder into medium mixing bowl. Cream butter in mixing bowl. Add sugars and beat on high speed until smooth and fluffy. Add egg and mix thoroughly. Beat in the melted chocolate on medium speed. Using the lowest speed, blend in one fourth of the flour mixture and one third of the milk. Repeat with remaining flour and milk, dividing into two additions. Continue beating until batter is well mixed. Pour into pan and spread evenly. Bake 25 minutes, or until cake tester comes out clean. Cool in pan 5 minutes. Invert onto cake rack. Carefully remove paper; cool cake completely. Oil inner side of 9 x 3 springform pan. Put cake layer in springform pan.

To make the mousse: Chill large mixing bowl and beater for whipped cream. Refrigerate 2 cups of cream. Sprinkle gelatin over water in a small cup; let stand 5 minutes while doing chocolate mixture. Combine white chocolate and remaining 1/2 cup cream in a double boiler or in a heat-proof bowl over hot but not simmering, water over low heat. Stir occasionally when partially melted; do not let any water splash into the chocolate. When melted, remove from pan of water and whisk until smooth. Whisk in butter.

Set cup of gelatin in a shallow pan of hot water over low heat and melt, stirring often, for about 3 minutes. Stir into chocolate mixture. Add egg yolks one at a time, stirring vigorously after each addition.

In a dry bowl, beat egg whites using dry beaters at medium speed until soft peaks form. Gradually beat in sugar and continue beating until whites are stiff and shiny but not dry. Fold 1/4 of the whites into the chocolate mixture. Return mixture to the egg whites and fold gently until blended. Whip cream in the chilled bowl until nearly stiff. Fold cream into chocolate mixture, blending thoroughly. Pour white chocolate mousse into prepared pan. Smooth top and refrigerate for about 4 hours, or until set.

To make the dark chocolate glaze: Combine the dark chocolate, butter, and water in a double boiler over barely simmering water. Let melt; stir until smooth. Remove from pan; let cool to room temperature. It will thicken.
Pour dark chocolate glaze over center of chilled mousse and spread to cover. Just before chocolate hardens, precut slices just through the chocolate layer.

To make the Frangelico cream: Bring the milk and cream to a boil over medium heat. Remove from heat. Beat the egg yolks and sugar together in a mixing bowl until light in color. Slowly pour in the heated milk and cream, beating to blend. Transfer mixture back to saucepan and cook over medium heat, stirring constantly, until the mixture thickens and coats the back of a spoon. Remove from stove and strain through a fine-meshed sieve. Let cool. Stir in the Frangelico.

To serve: Release the chocolate mousse cake from the springform pan and put on a cake plate. Cut into slices. Spoon Frangelico Cream onto serving plates. Place a slice of chocolate mousse cake over the sauce. Top with a sprinkling of coarsely ground hazelnut praline.