Directions

• For the praline paste
• Roast the hazelnuts for 10 minutes at 350°F. Prepare a baking sheet lined with greased parchment paper.
•  Pour the sugar and water into a pan and cook until the syrup caramelizes, and reaches an amber color. Take from the heat and add the hazelnuts. Then pour the contents onto the prepared baking sheet and leave to cool.
• Using a blender, mix everything until you obtain a semi-liquid texture.
• For the hazelnut mousse
• Whip the heavy cream, reserve in the fridge.
• Hydrate the gelatin in a tablespoon of cold water. Then put in a microwave for 30 seconds, until melted. Heat the milk, and shut off the heat, add the gelatin, and mix well.
• Melt the white chocolate and milk chocolate in the microwave, in two separate medium bowls. Pour half the milk and gelatin over each chocolate, and mix each one well.
• Add 3 Tablespoon of the hazelnut praline paste to each bowl of chocolate, and then add half (85 g or approximately 1/4 cup) of the whipped cream to each.
• I used a Silikomart silicone dome mould for the mousse, but any 7 or 8 inch cake pan, lined with plastic wrap could be used here. Pour the white chocolate mousse in the mold first, then add the second mousse, leveling them with an offset spatula. Place in the freezer for at least 8 hours – if using a silicone mould, place it on a baking sheet or inside a larger cake pan for stability first.
• For the cocoa hazelnut shortcrust pastry
• In a medium bowl, mix the butter cut into small pieces, the flour, the confectioners’ sugar, the hazelnut flour, hazelnut praline, the cocoa and the salt until the mixture is well sanded.
• Add the egg and mix until the dough begins to form a ball. Let it chill for one hour. Roll out the dough to 2mm, or 1/8th of an inch between plastic wrap. If you use a 9 inch tart pan with removable bottom, grease and line the bottom with parchment paper. If using a tart ring, line and grease a baking sheet with parchment paper.
• Line the tart pan with the dough, covering evenly the bottom and the sides. If using a tart ring, cut out a 10 inch circle and place it on the baking sheet, then cut out strips for the edges and place them inside the ring. Press the ring onto the 10 inch circle, and cut the access dough. Freeze for 20 minutes while you preheat the oven to 320 degrees Fahrenheit.
• Remove the tart from the freezer. Prick the bottom with a fork, line it with parchment or foil, and fill with pie weights or dry rice or beans. Bake for 20 minutes.
• For the hazelnut cream
• Whisk together the hazelnut flour, the confectioners’ sugar, and the salt. add the butter, then the egg. When the crust is finished baking, spoon in it. Continue baking at 320°F for 15 minutes. Let it cool on a cooling rack.
• For the milk chocolate ganache
• Heat the cream. Pour it over the chocolate and the butter cut into pieces, mix until smooth. Pour into the tart base. Place in the fridge to set.
• For the mirror glaze
• Hydrate the gelatin for 10 minutes in a tablespoon of cold water. Heat in the microwave until melted. Heat the heavy cream.
• In a saucepan, bring the water, sugar and glucose mixture to 103°. Add the hot cream and then the gelatin. Mix well.
• Pour over the chocolate and the praline paste and mix using an immersion blender, avoiding making bubbles, for two minutes. Let it rest until it reaches 95 to 100°F.
• To assemble
• Remove the tart from the fridge, and from the tart pan – or the ring, if using. Place on a serving plate.
• When the glaze reaches the right temperature, take the mousse from the freezer, and unmold it. Place a glass upside down over a plate, and the frozen mousse on top of the glass, centered. Pour the glaze evenly over the mousse. Let it drip for a couple of minutes.
• Place the mousse in the center of the tart, and decorate with crushed hazelnuts, if desired – they also will cover any further dripping of the glaze.