Paris Brest with Hazelnut Whipped Cream

Adapted from Epicurious.com

For praline

• 1 cup hazelnuts
• 1/4 cup sliced almonds
• 1/2 cup granulated sugar

For cream filling

• 1 cup whole milk
• 3 large egg yolks
• 1/3 cup granulated sugar
• 3 tablespoons cornstarch
• 1/4 teaspoon salt
• 2 tablespoons unsalted butter
• 1/2 teaspoon vanilla
• 3/4 cup chilled heavy cream

For choux pastry

• 1/2 cup water
• 1/2 cup milk
• 1 stick (1/2 cup) unsalted butter, cut into 1/2-1 inch cubes
• 1 teaspoon granulated sugar
• 1/2 teaspoon salt
• 1 cup all-purpose flour
• 4 whole large eggs
• Water
• Sliced almonds, for garnish
• Confectioners’ sugar, for dusting

Make praline

Put oven rack in middle position and preheat oven to 350°F.

Toast hazelnuts in a shallow baking pan in oven until skins split and nuts are golden, 10 to 15 minutes.  Remove from oven (leave oven on), then wrap hazelnuts in a kitchen towel and let steam 5 to 10 minutes.  Rub hazelnuts in towel to remove loose skins (some skins may not come off), then transfer hazelnuts to a small bowl, discarding skins.  While hazelnuts steam, toast almonds in baking pan until golden, 5 to 8 minutes, then add to bowl with hazelnuts. Lightly grease pan and set aside.

Cook sugar in a dry small heavy skillet over moderate heat, swirling skillet, until sugar begins to melt, about 2 minutes.  Continue to cook, swirling skillet, until sugar is melted into a deep golden caramel, 2 to 3 minutes more.  Remove from heat and, working quickly, stir in nuts to coat, then transfer mixture to greased baking pan, spreading slightly.  Let stand at room temperature until hardened and cool, about 30 minutes.

Transfer praline to a heavy-duty sealable plastic bag and seal bag, pressing out excess air.  Coarsely crush praline in bag using a rolling pin or bottom of a heavy skillet, then transfer three fourths to a food processor and purée until it becomes a smooth, creamy "butter," 3 to 4 minutes.  Reserve remaining crushed praline for garnish.

Make cream filling

Bring milk to a simmer in a 2½-3 quart heavy saucepan over moderate heat.  While milk heats, whisk together yolks, sugar, cornstarch, and salt in a heatproof bowl.

Add hot milk to yolk mixture in a stream, whisking, then transfer mixture to saucepan and bring to a simmer over moderate heat, whisking (mixture will become thick and lumpy).  Simmer, whisking constantly, 3 minutes (mixture will become smooth).  Remove from heat and stir in butter and vanilla.  Transfer to a clean bowl and chill pastry cream, cover its surface with wax paper, until cold, at least 1 hour.

Beat heavy cream in a bowl with an electric mixer until it just holds stiff peaks.  Beat pastry cream in a large bowl with mixer until smooth, then add praline "butter" and beat until incorporated.  Fold in whipped cream, one third at a time, gently but thoroughly.  Transfer the mixture to a pastry bag and chill until ready to use. 

Make choux pastry

Put oven rack in middle position and preheat oven to 375°F.  Cut a piece of parchment paper to fit in a sheet tray.  Trace 8 circles measuring 2½-3 inches in diameter with a pencil on to the parchment paper.  The circles should be 2-inches apart from each other.  Turn paper over (circles will still be visible) and put on the baking sheet.

Bring water and milk to a boil with butter, granulated sugar, and salt in a 3-quart heavy saucepan over high heat, then, reduce heat to moderate.  Add flour all at once and cook, stirring vigorously with a wooden spoon, until mixture pulls away from side of pan, about 1 minute.  Continue to cook and stir vigorously (to dry-out mixture) 3 minutes more.  Remove pan from heat and cool mixture, stirring occasionally, until warm to the touch, 5 to 10 minutes.  Add whole eggs 1 at a time, stirring vigorously after each addition until dough is smooth.

Transfer dough to pastry bag fitted with plain tip.  Pipe 1 ring over the circles traced on the parchment paper.  Pipe a second ring slightly offset to the center on top of each ring.  Dip your finger or a pastry brush in water and gently smooth out any tail ends of the dough that may be sticking up.  Lightly wet the top of the pastry with water.  Scatter almonds over the tops of the pastries. 

Bake choux pastry until golden and puffed, about 8-10 minutes, then reduce oven temperature to 350°F and continue to bake until deep golden and firm to the touch, about 8-10 more minutes.  Prick sides of pastry in 3 to 4 places with tip of a small sharp knife (to release steam), turn off the oven and leave the door slightly ajar.  Allow the pastry to sit in the oven for 15-20 minutes to continue to dry out the center of the dough then remove from the oven and allow to cool to room temperature. 

Halve pastry horizontally with a serrated knife and carefully invert top onto work surface.  Pipe hazelnut cream into bottom half of pastry, then carefully reinvert top half over it.  Sprinkle top with reserved praline and dust with additional confectioners’ sugar.