1 cup (250 mL)hazelnuts (filberts), toasted and skins removed (see below)
1 cup (250 mL)granulated sugar, divided
4 egg whites, at room temperature
1/2 tsp (2.5 mL)cream of tartar
5 oz (145 g)dark or bittersweet chocolate, coarsely chopped
1 1/3 cups (325 mL)whipping cream (35%), divided
Step 1 Preheat oven to 325°F (180°C).
Step 2 Process hazelnuts with 1/4 cup (50 mL) of sugar in food processor until coarsely chopped. Remove 2 tbsp (30 mL); reserve for garnish. Continue processing hazelnuts until finely chopped.
Step 3 Line bottoms of two baking sheets with parchment paper. On each, draw two 4 x 8-inch (10 x 20 cm) rectangles. Turn paper over; rectangles should be visible.
Step 4 Beat egg whites with electric mixer until frothy. Add cream of tartar and beat until soft peaks form. Add remaining sugar, about 1 tbsp (15 mL) at a time, beating until sugar is dissolved and stiff peaks form. Gently fold in hazelnuts. Spoon one quarter of the mixture over each rectangle; spread evenly to fill space.
Step 5 Bake in a preheated 325°F (180°C) oven until crisp on the outside and light golden in colour, about 25 minutes. Let cool on baking sheets.
Step 1 When ready to assemble, heat chocolate and 1/3 cup (75 mL) whipping cream in microwave on High power until chocolate is partially melted, about 40 seconds. Stir until completely melted; set aside.
Step 2 Whip remaining cream on high until stiff peaks form. Gently fold in chocolate until blended.
Step 3 Carefully peel one meringue from parchment paper; place on serving plate. Spread one quarter of filling over meringue. Continue layering remaining meringues and filling, ending with layer of filling. Sprinkle reserved hazelnuts over top.
Step 4 Refrigerate for at least 2 hours or overnight before cutting into slices with serrated knife to serve.