Instructions

MAKE THE DARK CHOCOLATE SHELLS (prepare 1 day ahead):
1. Ensure 8 small cup molds (approximately 4 oz capacity) are completely clean and dry.
2. Temper dark chocolate using seeding method: Melt 12 oz chocolate in double boiler to 115°F (46°C), remove from heat, add remaining 4 oz chopped chocolate and stir until temperature drops to 82°F (28°C), then gently rewarm to 89-91°F (32-33°C).
3. Using small pastry brush, paint thin, even coat of tempered chocolate inside each mold, ensuring complete coverage with no gaps or thin spots.
4. Refrigerate molds 5 minutes until first coat sets and pulls slightly away from mold edges.
5. Apply second coat of tempered chocolate for strength, paying special attention to edges and base for structural integrity.
6. Refrigerate again 5 minutes until second coat sets.
7. Apply third coat for maximum strength, ensuring total thickness of about 1/8-inch throughout.
8. Refrigerate final time 15 minutes until completely firm.
9. Carefully unmold dark chocolate cups by gently flexing molds (cups should release easily if properly tempered).
10. Store at cool room temperature (60-65°F) until ready to fill.

PREPARE THE HAZELNUT CORE (make at least 2 hours ahead - needs freezing):
11. Preheat oven to 350°F (175°C). Spread 1 cup whole hazelnuts on baking sheet.
12. Toast hazelnuts 10-12 minutes until fragrant and skins begin to crack.
13. While still hot, transfer to clean kitchen towel, wrap, and rub vigorously to remove as much skin as possible (some skin remaining is fine).
14. In small heavy-bottomed saucepan, combine 1/4 cup sugar and 2 tablespoons water without stirring.
15. Cook over medium-high heat without stirring until mixture turns deep amber color (350°F/177°C), about 6-8 minutes.
16. Working quickly and standing back, add toasted hazelnuts and stir with heat-resistant spatula to coat completely.
17. Immediately pour onto parchment-lined baking sheet and spread in single layer.
18. Cool completely until hardened, about 20 minutes.
19. Break hardened hazelnut praline into pieces and transfer to food processor.
20. Add hazelnut paste, butter, and pinch of sea salt to food processor.
21. Process until thick, cohesive paste forms, scraping down sides as needed (should hold together when pressed).
22. Roll paste into 8 small balls (about 1 inch diameter each) and place on parchment-lined plate.
23. Freeze balls until very firm and solid, at least 1 hour (can be made 1 day ahead and kept frozen).

MAKE THE HAZELNUT PRALINE FOR GARNISH (can be made 2 days ahead):
24. Preheat oven to 350°F (175°C). Spread 1/2 cup whole hazelnuts on baking sheet.
25. Toast hazelnuts 10-12 minutes until fragrant, then roughly chop into quarters.
26. In small heavy-bottomed saucepan, combine 1/2 cup sugar and 2 tablespoons water without stirring.
27. Cook over medium-high heat without stirring until mixture turns deep amber color (350°F/177°C), about 6-8 minutes.
28. Working quickly, add chopped toasted hazelnuts and pinch of salt, stirring to coat completely.
29. Immediately pour onto parchment-lined baking sheet and spread as thin as possible.
30. Cool completely until hardened, about 20 minutes.
31. Break or crush praline into small irregular pieces (pea-sized).
32. Store in airtight container at room temperature.

PREPARE THE HAZELNUT CARAMEL (can be made 1 day ahead):
33. Warm 1/3 cup heavy cream in microwave or small saucepan until hot to touch but not boiling. Keep warm.
34. In heavy-bottomed saucepan, combine 1/2 cup sugar and 2 tablespoons water without stirring.
35. Cook over medium-high heat without stirring until mixture turns amber color (350°F/177°C), about 6-8 minutes, watching carefully toward end.
36. Remove from heat and carefully whisk in warmed cream while standing back (mixture will bubble and steam vigorously).
37. Once bubbling subsides, whisk in butter until smooth.
38. Stir in chopped toasted hazelnuts, sea salt, and hazelnut liqueur if using.
39. Cool to room temperature until thick but still pourable, about 30-45 minutes.
40. Cover and refrigerate if making ahead. Bring to room temperature before using.

MAKE THE PROPERLY SET CHOCOLATE MOUSSE (prepare on assembly day):
41. In small bowl, sprinkle 1.5 teaspoons unflavored gelatin evenly over 3 tablespoons cold water and let bloom undisturbed for 5 minutes (gelatin will absorb water and become spongy).
42. After blooming, warm gelatin gently in microwave for 10-15 seconds or over very low heat until completely dissolved and clear (do not boil).
43. Place chopped dark chocolate in medium heatproof bowl and melt in double boiler or microwave, stirring until completely smooth.
44. Cool melted chocolate to about 95-100°F (35-38°C), stirring occasionally, until lukewarm to touch.
45. Stir dissolved gelatin into lukewarm melted chocolate immediately while both are still warm, mixing until completely incorporated.
46. In small bowl, whisk egg yolks until pale yellow and slightly thickened, about 1 minute.
47. Fold whisked egg yolks into chocolate-gelatin mixture until well combined and smooth.
48. In large clean bowl with clean beaters, beat egg whites with pinch of salt until soft peaks form.
49. Gradually add 2 tablespoons sugar while beating and continue until stiff, glossy peaks form.
50. In separate bowl, whip heavy cream to medium peaks (peaks should bend slightly when beaters are lifted).
51. Gently fold whipped cream into chocolate base in three additions using rubber spatula, adding vanilla extract with final addition.
52. Finally, fold beaten egg whites into mixture in two additions, being careful not to deflate.
53. Use mousse immediately for assembly.

ASSEMBLE THE MOUSSE CUPS:
54. Have all components ready: dark chocolate cups, frozen hazelnut core balls, freshly prepared mousse, room temperature caramel, praline pieces, and chocolate ash mixture.
55. Transfer mousse to large piping bag fitted with large round tip, or use large spoon.
56. Pipe or spoon chocolate mousse halfway into each dark chocolate shell (about 1/3 cup per cup).
57. Gently tap cups on counter to remove air bubbles and settle mousse.
58. Remove frozen hazelnut praline balls from freezer and quickly press one ball into center of mousse in each cup, submerging completely so top is level with mousse surface.
59. Pipe or spoon more mousse over each core to completely cover and fill cup nearly to top, leaving about 1/4-inch from rim.
60. Smooth top surface with small offset spatula or back of spoon for neat finish.
61. Gently tap cups again to remove any remaining air bubbles.
62. Refrigerate assembled cups uncovered 5-6 hours minimum until mousse is firmly set throughout and doesn't jiggle when gently shaken.
63. Once set, cover loosely with plastic wrap if storing longer.

FINAL GARNISHING AND SERVING:
64. Just before serving, spoon approximately 2 tablespoons hazelnut caramel over top of each mousse cup, spreading to edges.
65. Sprinkle crushed hazelnut praline pieces generously over caramel layer on each cup.
66. In small bowl, mix together Dutch-process cocoa powder, black cocoa powder, and powdered sugar until well combined.
67. Using fine-mesh sieve, lightly dust chocolate ash mixture over top of each cup for dramatic modern finish (apply sparingly for subtle effect).
68. Place each cup on individual serving plate.
69. Serve chilled with small dessert spoons.
70. When cut or spooned, each serving should reveal dark chocolate shell, properly set mousse, surprise hazelnut core center, and rich caramel topping with praline crunch.

STORAGE AND SERVING:
Chocolate cups can be made 1-2 days ahead and stored at cool room temperature
Frozen hazelnut cores can be made 1 day ahead and kept frozen
Praline garnish can be made 2 days ahead and stored airtight at room temperature
Hazelnut caramel can be made 1 day ahead and refrigerated
Assembled mousse cups (without caramel and garnish) can be refrigerated up to 1 day
Add caramel, praline, and chocolate ash just before serving
Serve chilled for optimal texture and dramatic reveal of hazelnut core