Mix the room-temperature butter and the icing sugar together in the bowl of a planetary mixer. Once creamed together, add the salt, lemon zest and vanilla seeds. Mix.
Add one egg yolk at a time without stopping the planetary mixer and when everything is mixed together evenly, switch off. Sift the flour well then add it to the mixture, running the planetary mixer at low speed. As soon as the mixture is smooth (a few seconds), switch off and tip onto the work surface. Bring the pastry dough together with your hands, then roll it out on a sheet of baking paper. Cover with another sheet of baking paper and, with the aid of a rolling pin, roll it out into a disc about 4 mm thick. Using a small knife, cut out a disc about 30 cm in diameter and trim away the excess pastry. Place in the refrigerator, wrapped in cling film or baking paper. Keep the rest of the pastry in the freezer for other uses.
COOKING THE BASE
After about an hour, remove the pastry disc from the refrigerator and place it in a lightly buttered 23/24 cm tart tin. Prick the base all over with a fork. Trim any excess pastry from the edges with a small knife. Place in the refrigerator while waiting for the oven to reach 160° C. Place a slightly crumpled sheet of baking paper inside the pastry case and fill with baking beans or rice. Bake blind for about 35 to 40 minutes or until golden brown (the pastry will start to shrink away slightly from the edge of the baking tin). Remove from the oven and allow to cool.
PREPARING THE CUSTARD
Pour the milk into a saucepan along with the spent vanilla pod and the sugar. Just before it comes to the boil, take a few tablespoons of milk and mix into the cornstarch in a bowl (use a whisk). Once the cornstarch is dissolved and lump-free, add it to the milk together with the honey and stir with a whisk until the mixture has thickened. Pour the custard into a bowl, add a knob of butter and whip well to make it glossy. Cover with cling film placed directly on top of the custard, leave to cool and then place in the refrigerator. Once the custard has cooled, whip the cream. Use the same whisks to loosen the milk custard, which will have hardened slightly during cooling. Fold the whipped cream a little at a time into the milk custard, using a spatula and folding gently from the bottom upwards so as to keep the air in. Transfer the milk custard into a piping bag fitted with a smooth nozzle and place in the refrigerator until use.
ASSEMBLING THE SWEET
Cut the figs into thin slices. Warm the honey a little and add a few teaspoons of Giusti Condiment with Balsamic Vinegar of Modena PGI and Fig. Mix.
Spread the fig jam over the pastry case, then pipe the custard on top all the way to the edge. Arrange the fig slices on top. Brush with the warm honey sauce. If you like, add some toasted hazelnuts.