Instructions

MAKE THE CHOCOLATE PASTRY:
In food processor, pulse flour, cocoa powder, sugar, and salt until combined. Add cold butter and pulse until mixture resembles coarse crumbs. Add egg yolk and 2 tablespoons ice water. Pulse until dough just comes together, adding more water if needed. Form into disk, wrap in plastic, and refrigerate 1 hour.

Roll out pastry on floured surface to 1/8-inch thickness (slightly thinner than traditional to ensure proper baking and crispness). Transfer to 9-inch tart pan with removable bottom, pressing into corners without stretching. Trim excess, leaving 1/2-inch overhang. Fold overhang in to reinforce sides and create sturdy edge.

Dock bottom with fork. Line with parchment paper and fill with pie weights or dried beans. Refrigerate 30 minutes. Preheat oven to 375°F (190°C). Blind bake 15 minutes. Remove weights and parchment, brush with beaten egg wash. Bake additional 10-12 minutes until pastry is fully set, dry to touch, and evenly colored. Cool completely in pan on wire rack.

MAKE THE HOMEMADE PEANUT BUTTER:
Process peanuts in food processor 5-7 minutes, scraping down sides every minute. Mixture will go from crumbly to creamy. Add oil only if needed for desired consistency. Add pinch of salt. Process until completely smooth. Set aside 1/4 cup (65g) for caramel and 3 tablespoons for mousse. Reserve remainder for truffles.

MAKE THE SALTED CARAMEL LAYER:
Heat sugar in heavy-bottomed saucepan over medium heat without stirring. As sugar begins to melt around edges, gently swirl pan to distribute heat. Continue cooking until all sugar melts and turns deep amber color (about 8-10 minutes). Watch carefully to avoid burning.

Remove from heat. Immediately add butter, whisking constantly (mixture will bubble vigorously). Once butter incorporates, slowly add cream while whisking (be careful of steam). Whisk in salt and 1/4 cup peanut butter until smooth. Let cool 10 minutes, then pour into cooled tart shell. Spread evenly. Refrigerate 30 minutes until set but not hard.

MAKE THE CHOCOLATE PEANUT MOUSSE:
Melt chocolate in double boiler or microwave in 30-second intervals, stirring until smooth. Stir in 3 tablespoons peanut butter until combined. Let cool to room temperature but not set.

In separate bowl, beat egg whites with pinch of salt until soft peaks form. Gradually add sugar and beat until stiff glossy peaks form. In another bowl, whip cream to soft peaks.

Whisk egg yolks into cooled chocolate mixture one at a time until smooth. Gently fold in one-third of whipped cream to lighten mixture. Fold in remaining cream until just combined. Finally, fold in beaten egg whites in two additions until no streaks remain.

Spread mousse over set caramel layer in tart shell. Smooth top. Refrigerate at least 2 hours until mousse is set and stable.

MAKE THE CHOCOLATE GANACHE:
Place chopped chocolate in heatproof bowl. Heat cream in saucepan until just beginning to simmer (small bubbles around edges). Pour hot cream over chocolate and let sit 2 minutes. Starting from center, whisk in small circles, gradually working outward until smooth. Add butter and whisk until glossy and incorporated. Let cool 10 minutes until slightly thickened but still pourable.

Pour ganache over chilled mousse layer, tilting tart to create even coating. Use offset spatula to smooth if needed. Refrigerate 30 minutes to set ganache.

MAKE THE PEANUT POWDER TRUFFLES:
Melt chocolate and stir in heavy cream and 1 tablespoon peanut butter until smooth. Let cool until thick enough to scoop. Using small spoon or melon baller, form into 12-15 small truffle balls. Roll in peanut powder to coat completely. Refrigerate until ready to use.

TO MAKE PEANUT POWDER (if not available commercially): Process 1/4 cup roasted peanuts with 2 tablespoons maltodextrin powder (N-Zorbit or similar) in food processor until fine powder forms. This creates dry, coatable powder from oily peanuts.

ASSEMBLE AND GARNISH:
Arrange peanut powder truffles around edge of tart. Scatter toasted chopped hazelnuts over center. Add chocolate curls or shavings. Dust lightly with extra peanut powder if desired.

Refrigerate until 30 minutes before serving. Remove tart from pan, transfer to serving plate. Let stand at room temperature 20-30 minutes before slicing for best flavor and texture. Use sharp knife, wiping clean between cuts.

CHEF'S NOTES:
The chocolate pastry should be rolled thinner than traditional pastry (1/8-inch) to ensure it bakes fully and provides crisp base rather than thick, undercooked layer. Blind baking with egg wash creates sealed, crisp shell that holds rich filling.

Homemade peanut butter provides fresher flavor than commercial versions and allows control over texture and saltiness. Be patient during processing - peanuts will transform from powder to butter.

For salted caramel, have all ingredients measured and ready before starting. Caramel darkens quickly once it starts. Deep amber color provides complex flavor, but watch carefully to avoid burnt taste.

Mousse requires gentle folding technique. Incorporate egg whites last and fold just until combined to maintain maximum volume and light texture. Over-mixing deflates mousse.

Peanut powder coating can be made using maltodextrin (N-Zorbit), which absorbs oils and converts nut butter into dry powder. This specialized ingredient is available online or in molecular gastronomy suppliers. Alternatively, use finely ground toasted peanuts, though coating won't be as dry.

Yield: One 9-inch tart (10-12 servings)