Chocolate Hazelnut Cake with Praline Chocolate Crunch

Ingredients

• 0.5 cup butter (or ground roasted hazelnuts)
• 12 servings warm chocolate glaze 
• 1 cup cocoa powder unsweetened
• 2 tablespoons plus 
• 3.5 ounces chocolate dark 72% chopped (do not exceed cacao)
• 8 large eggs 
• 1 cup flour all-purpose
• 1 cup hazelnuts (reserved from praline chocolate crunch)
• 0.3 cup hazelnuts 
• 1.5 cups hazelnuts toasted
• 1.8 cups cup heavy whipping cream chilled divided
• 1 pinch kosher salt 
• 4 ounces chocolate chopped (such as Lindt or Scharffen Berger)
• 0.5 cup orange liqueur 
• 1.8 cups oatmeal cornflakes crushed
• 1 cup sugar divided
• 5 tablespoons butter unsalted cubed room temperature
• 1 teaspoon vegetable oil 

Equipment

• food processor
• bowl
• frying pan
• baking sheet
• sauce pan
• baking paper
• oven
• aluminum foil
• pastry brush

Directions

1. Line 2 rimmed baking sheets with parchmentpaper. Stir sugar and 1/3 cup water in a smallsaucepan over medium-low heat untilsugar dissolves. Increase heat and cookwithout stirring, occasionally swirling panand brushing down sides with a wet pastry brush, until amber in color, 7–8 minutes.Stir in hazelnuts, then pour onto 1 preparedsheet, separating nuts.
2. Let cool.
3. Transfer candied nuts to a food processor.
4. Add hazelnut oil and purée until smooth tomake praline paste.
5. Combine both chocolates and 3 tablespoonspraline paste in a medium metal bowl(reserve remaining praline paste for pralinemousse layer). Set bowl over a saucepanof simmering water and stir until chocolateis melted and mixture is smooth.
6. Removefrom heat and stir in salt, then cereal.
7. Spreadout in a thin layer (about 1/8") on second preparedbaking sheet. Chill until set, about30 minutes.DO AHEAD: Can be made 1 dayahead. Cover and keep chilled. Cover andchill remaining praline paste.
8. Preheat oven to 375°F. Line a 17x11x1"sheet pan with parchment paper; butterpaper. Sift flour and cocoa powder intoa medium bowl and set aside. Separate4 eggs, placing yolks in a large bowl andwhites in a medium bowl. Using an electricmixer, beat yolks with 1/2 cup sugar onmedium speed until thick and light yellow,about 3 minutes. Beat in 4 whole eggs, oneat a time, blending well between additions.
9. Using clean, dry beaters, beat egg whiteswith remaining 1/2 cup sugar and corn syrupuntil slightly thickened and frothy, about2 minutes.
10. Add egg-white mixture to egg-yolkmixture and beat to blend.
11. Addflour–cocoa powder mixture; fold just toblend.
12. Spread out evenly on preparedbaking sheet.
13. Bake until a tester inserted into centerof cake comes out clean, about 15 minutes.
14. Let cool completely. Invert cake onto a largecutting board or baking sheet and peel offparchment.
15. Brush cake all over with brandy.DO AHEAD: Can be made 1 day ahead. Storeairtight at room temperature.
16. Bring cream to a boil in asmall saucepan. Purée hot cream, hazelnutbutter, and salt in a food processor.
17. Let coolto room temperature. With machine running,add butter, 1 tablespoon at a time, puréeing untilsmooth between additions. DO AHEAD:Can be made 1 day ahead. Cover and chill.Return to room temperature before using.
18. Combine chocolate,praline paste, and butter in a mediumbowl. Bring 3/4 cup cream to a boil in a smallsaucepan; pour over chocolate mixture.
19. Letstand for 1 minute, then stir until melted andsmooth. Beat remaining 1 cup chilled creamuntil soft peaks form. Fold whipped creaminto chocolate mixture. DO AHEAD: Can bemade 1 day ahead. Cover and chill.
20. Spread nut ganache overcake and chill in freezer until set, about15 minutes.
21. Spread mousse over ganacheand chill in freezer until set, about 15minutes.
22. Cut cake crosswise into thirds;stack layers on top of each other. Trimedges, then spread Chocolate Glaze overtop and sides of cake. Freeze until set,about 1 hour.
23. Place in refrigerator and chillovernight. DO AHEAD: Can be made 2 daysahead. Tent with foil and keep chilled.
24. Let cake stand at room temperaturefor 30 minutes before serving. Break uppraline chocolate crunch into large shardsand arrange on top of cake.
25. Garnish withroasted hazelnuts.