Lemon Pistachio Mousse Tart

Prepare the Tart Shell: In a bowl, combine all-purpose flour, powdered sugar, and a pinch of salt. Cut in the cold cubed butter until the mixture resembles coarse crumbs.

Add the egg yolk and 1-2 tablespoons of cold water to the flour mixture. Mix until a dough forms. Do not overwork. Flatten the dough into a disc, wrap in plastic, and chill for at least 30 minutes.

Roll out the chilled dough on a lightly floured surface to fit a 9-inch tart pan. Carefully transfer the dough to the pan, pressing it gently into the bottom and up the sides. Trim any excess dough. Prick the bottom with a fork and chill for another 15 minutes. Preheat oven to 375°F (190°C).

Blind bake the tart shell: Line the chilled tart shell with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes, then remove weights and parchment. Bake for another 5-7 minutes, or until golden brown. Let cool completely.

Prepare the Vanilla Sponge: Preheat oven to 375°F (190°C) as per the recipe. Line a small baking sheet or round cake pan (about 6-inch) with parchment paper. In a bowl, whisk egg yolks and honey until light and fluffy.

In a separate clean bowl, whip egg whites with a pinch of salt until soft peaks form. Gradually add 35g sugar and continue to whip until stiff, glossy peaks form.

Gently fold a third of the whipped egg whites into the egg yolk mixture. Then, gently fold in the remaining egg whites. Sift in the cake flour and fold until just combined. Fold in the canola oil and vanilla extract.

Pour the batter into the prepared pan and spread evenly. Bake for 8-9 minutes until golden brown and a toothpick inserted comes out clean. Let cool, then cut out a circle to fit inside the tart shell.

Prepare the Pistachio Ganache: Gently melt the white chocolate in a heatproof bowl over a double boiler or in short bursts in the microwave.

In a small saucepan, gently heat the heavy cream until just simmering. Pour the hot cream over the melted white chocolate. Let sit for 1 minute, then stir until smooth. Stir in the pistachio paste and 10g butter until fully incorporated. Chill the ganache for at least 30 minutes until it's spreadable.

Prepare the Lemon Mousse: Hydrate the gelatin sheets in cold water for 5-10 minutes until soft. In a saucepan, whisk together lemon juice, 55g sugar, lemon zest, 50g whole egg, and 20g egg yolk. Cook over medium-low heat, stirring constantly, until the mixture thickens to a custard consistency (about 175°F / 80°C).

Remove from heat. Squeeze excess water from the gelatin and stir it into the hot lemon custard until fully dissolved. Stir in 35g unsalted butter until melted and smooth. Transfer the custard to a bowl and let it cool to room temperature, stirring occasionally.

In a separate cold bowl, whip 170g heavy cream until soft peaks form. Gently fold the whipped cream into the cooled lemon custard in several additions until light and airy.

Assemble the Tart: Spread an even layer of the chilled pistachio ganache into the bottom of the cooled tart shell. Place the cut vanilla sponge disc over the ganache layer.

Pour or pipe the lemon mousse over the sponge layer, spreading it evenly to the edges. Gently tap the tart on the counter a few times to release any air bubbles. Chill the tart in the refrigerator for at least 1-2 hours, or until the mousse is fully set.

Once set, carefully remove the tart from the pan. Decorate with additional lemon zest, chopped pistachios, or fresh berries before serving.