Bittersweet chocolate cake with raspberry sauce (Melissa Tam, highly recommended!)

A flourless chocolate cake from Williams-Sonoma Savouring Desserts Cookbook, p. 32 (Serves 12)

Cake
1 C (5oz/155g) plus 2 Tbsp hazelnuts (filberts),
3 Tbsp plus ¾ C (6oz/ 185g) granulated sugar,
6 eggs - separated,
1 Tsp vanilla extract,
¾ C (6oz/ 185g) unsalted butter,
6 oz (185g) bittersweet chocolate - coarsely chopped

Sauce
1 ½ C (6oz/ 185g) raspberries.
3 Tbsp superfine (caster) sugar, or more to taste.
1 Tsp framboise or kirsch

1. Preheat oven to 350 F (180 C). Butter the bottom and sides of a 9-inch (23-cm) springform pan. Dust with flour, tapping out excess.
   

2. In a food processor, combine the hazelnuts and 1 Tbsp of the granulated sugar. Pulse until the nuts are very finely ground; do not grind to a paste. (I lightly roasted the nuts for 8 –10 minutes at 350F the night before to remove some of the husk from the hazelnuts.)

3. In a stand mixer fitted with the whip attachment, combine the egg yolks, the ¾ C granulated sugar, and the vanilla and beat on high speed until pale and thick, 4-5 minutes, stopping to scrape down the sides of the bowl once or twice. (I would suggest that you use a large bowl for this.)
   

4. In a small saucepan over low heat, melt the butter. Remove from the heat, add the chocolate, and let stand until the chocolate melts, 2-3 minutes. Stir until smooth. In a bowl, using a whisk or a handheld electric mixer on medium-high speed, whip the egg whites until soft peaks form, then gradually add the remaining 2 Tbsps granulated sugar. Whip until the whites are firm and glossy.
   

5. With the stand mixer on low speed, add the chocolate mixture to the egg yolks. Beat until blended, stopping to scrape down the sides of the bowl once or twice. Add the ground nuts and beat just until incorporated; the batter will be stiff.
   

6. Stir in one-third of the egg whites to lighten batter, and then gently fold in the remaining whites in 2 batches. Pour the batter into the prepared pan. Bake until the centre is firm to the touch and the surface begins to crack, about 50 minutes (I found that the cake only took 35- 40 minutes to bake in my oven. I suggest that you start to check on the cake at 35 minutes). Transfer to a rack and let cool completely. Unclasp and remove the pan sides, then carefully slide the cake onto a flat serving plate.
   

7. To make the sauce, in a food processor, puree the raspberries until smooth. Add the 3 Tbsps superfine sugar and process until fully incorporated. Taste and add more sugar if desired. When sweetened to taste, pass the puree through a fine-mesh sieve place over a bowl to eliminate the seeds. Stir in the framboise or kirsch.