Ingredients 
Makes about 18 servings

Brownie Layers*
3.5 oz (100g) semisweet chocolate
3/4 cup (170g) butter
1 tsp (2g) instant coffee powder
1 tbsp (8g) unsweetened cocoa powder
1 cup (200g) sugar
1/2 tsp (3g) salt
3 eggs
1 tsp (5g) vanilla extract
3/4 cup (95g) flour
1 oz (30g) semisweet chocolate, chopped, divided in 3
Hazelnuts*
2 cups (300g) hazelnuts, whole, divided
Meringue Layers*
1/2 cup (75g) hazelnuts, toasted and grounded
1/2 cup (60g) powdered sugar, divided
4 tbsp (60g) sugar, divided
3/4 cup (95g) all-purpose flour
4 egg whites
1 tbsp (15ml) lemon juice
Pinch of salt
Chocolate Ganache for filling*
7 oz (200g) semisweet chocolate
3/4 cup (200g) whipping cream
Nutella Frosting*
5.5 oz (160g) semisweet chocolate
2/3 cup (160g) whipping cream
1/2 cup (60g) unsweetened cocoa powder
3/4 cup (200g) nutella
1 1/2 tsp (7g) vanilla extract
1 1/3 cup (300g) butter, room temperature
Chocolate Glaze*
7 oz (200g) semisweet chocolate, small pieces
1/4 cup (56g) butter
1/4 cup (50g) sugar
2/3 cup (160ml) milk
For decorating*
Ferrero Rocher truffles
chocolate chips/curls
chopped hazelnuts

Directions

Prepare brownie layers. Preheat oven to 350 degrees F (180C). Butter the sides and bottom of three 8 inch (20cm) round baking pans. Line the pans with parchment paper. Melt the chocolate and butter in a medium bowl, over bain-marie, stirring occasionally, until smooth. Stir in the sugar, then remove the bowl from the pan. Incorporate the eggs one at a time into the mixture and whisk until well combined. Stir in coffee powder, cocoa powder, the vanilla extract then add the flour and salt and stir well. Divide the batter evenly into the prepared pans. Sprinkle on the top of each about 1 tbsp (10g) chopped chocolate around the inner edge of the pans. Bake for about 18-20 minutes. Let the brownies cool completely. Toast the hazelnuts. Turn the oven to 325F (160C). Place the hazelnuts on a baking sheet and let them toast for 10 minutes. Rub the nuts to remove as much skin as possible. Let them cool completely. Prepare the meringue layers. Turn the oven to 200F (100C). Line a baking sheet with parchment paper and draw two 8 inch (20 cm) diameter circles. Take ½ cup (75g) toasted hazelnuts and place in the bowl of a food processor. Process until evenly ground. Transfer the the ground hazelnuts into a medium bowl and mix with half powdered sugar (¼ cup -30g) and half granulated sugar (2 tbsp -30g) and flour. Set aside. Whip egg whites with a pinch of salt until soft peaks form. Gradually add the rest of powdered sugar and granulated sugar and continue whipping until stiff peaks form, about 7 minutes. Mix in lemon juice. Fold in the hazelnuts and flour mixture. Transfer the mixture into a piping bag fitted with a ½ inch (1cm) plain tip. Following the drawn circles, pipe two disks of batter in a spiral. Bake the meringue disks for 1 hour and 30 minutes. Let them cool completely. Prepare chocolate ganache for filling. Place the chocolate and whipping cream into a heatproof bowl and melt over bain-marie. Cover and let it cool. Prepare Nutella frosting. Place the chocolate and whipping cream into a heatproof bowl and melt over bain-marie. Cover and refrigerate for 30 minutes. Place butter into a mixing bowl and start mixing for about 10 minutes until smooth and creamy. Add sifted cocoa powder and refrigerated chocolate ganache and mix on low until incorporated. Mix in nutella and vanilla extract and mix to combine. Transfer the frosting and chocolate ganache into piping bags fitted with ¼ inch (5mm) plain tips. Cake assembly. On a serving platter pipe a bit of frosting and place one brownie layer. Spread half of chocolate ganache. Add a meringue layer. Spread a bit less than 1/3 of nutella frosting. Add the second brownie layer. Spread a bit less than 1/3 nutella frosting. Add the second meringue layer. Spread the other half of chocolate ganache. And finally add the last brownie layer. Spread remaining nutella frosting on top and sides of the cake. Refrigerate the cake for 30 minutes. Meanwhile cut the remaining 1 ½ cups (225g) toasted hazelnuts in smaller pieces. Press the chopped hazelnuts onto the sides of the cake. Refrigerate for another 30 minutes Prepare chocolate glaze. Place chocolate, butter sugar and milk into a heatproof bowl and melt over bain-marie. Sieve the glaze. Place the cake over a smaller bowl or pan, placed in a baking sheet. Pour glaze to cover the top and edges. Refrigerate for 4-6 hours or overnight. The meringue layers needs to soften slightly, making the cake easier to slice. Decorate with Ferrero Rocher truffles, chopped hazelnuts and chocolate chips or curls.

Credit: Home Cooking Adventure