Recipe Detail Page

1. Place the oven rack in the middle position and preheat the oven to 375°F (190°C). Line the bottom of two 9-inch (23-cm) square cake pans with parchment paper and set aside.

2. Place the chocolate in a medium bowl and set over a pot of barely simmering water, making sure the bottom of the bowl doesn’t touch the water. Stir occasionally just until melted. Remove the bowl from the water and set aside. The chocolate should remain slightly warm.

3. Whisk the yolks just enough to break them up. Add the espresso and vanilla and whisk to combine. Set aside.

4. Place the whites in the bowl of an electric mixer fitted with the whisk attachment. Add a pinch of salt and beat the whites on medium-high speed until frothy. Add the sugar gradually and continue beating to stiff peaks, scraping down any sugar that might cling to the sides of the bowl.

5. Whisk the melted chocolate into the yolks espresso-vanilla mixture until smooth then fold in one-quarter of the beaten egg whites. Fold in the remaining whites lightly but thoroughly, just until no streaks remain.

6. Divide the batter between the 2 pans and bake for 10 minutes. Lower the oven temperature to 350°F (180°C) and continue baking 5 more minutes until the top of the cakes are dry and just beginning to crack. (The cakes will not rise very much). Transfer to a rack and cool completely.

7. For the frozen mousse, line the sides of 1 of the cake pans (with the cake layer still intact) with strips of parchment paper.

8. Chop the Toblerone bar into small pieces and set aside. In a large, heatproof mixing bowl, whisk together the 5 egg yolks, water, Kahlúa or Frangelico, vanilla and sugar. Place the bowl over a pot of boiling water, making sure the bottom of the bowl doesn’t touch the water. Whisk constantly until the mixture has thickened, lightened in colour and is hot to the touch. Remove from heat and add the chopped Toblerone bar. Whisk until fully melted. Add the toasted hazelnuts. Cool to room temperature.

9. Beat the whipping cream to stiff peaks and fold into the hazelnut mixture. Pour into the prepared pan and spread evenly. Turn the second cake layer out onto the hazelnut mixture and press down gently to level. Wrap well and freeze overnight.

10. Using a sharp knife, cut the “cake” into 4 even strips. Rotate 90 degrees and make 4 more even cuts, creating 16 squares. Cut the squares into triangles. Return to the freezer and just before serving, dust very lightly with cocoa powder.