For the cake:
1) Preheat the oven to 200C/Gas 6. Butter 8 individual baking tins.
2) Put both types of flour in a mixing bowl and stir in the ground pistachios, sugar and vanilla. In another bowl, beat the egg whites with a pinch of salt until stiff peaks form. Fold them very carefully into the flour mixture.
3) Quickly fold in the melted butter. Divide the batter between the baking tins and cook for 15 to 20 minutes or until the cakes are golden brown.
4) Remove the cakes from the tins and allow them to cool on a rack, brushing them from time to time with the pear liqueur.
For the custard:
1) Halve the Seckel pears lengthwise. Melt 115g of the sugar in a large saucepan (large enough to hold all the Seckel pear halves). Add the pear halves, cut side down, and cook until caramelized.
2) Blanch the Forelli pears in a pot of boiling water for 1 minute. Drain and cut in half lengthwise. Toss the pears with 115g of the sugar and roast in the oven until lightly browned.
3) Reduce the oven temperature to 170C/Gas 3. Combine the eggs and yolks in a mixing bowl. Bring the cream, vanilla bean seeds and remaining 115g of sugar to a simmer. Add about 240ml of the simmering cream mixture to the eggs and whisk to combine. Add the egg mixture to the simmering cream mixture and cook until thickened, about 4 minutes. Do not allow to boil.
4) Transfer the custard to individual serving ramekins or moulds, and arrange in a large baking dish. Pour water into the baking dish to halfway up the sides of the outside of the ramekins.
5) Place the baking tray in the oven. Bake until the custard is set then remove from the oven and cool.
6) Spoon the cooled custard over the finished cakes and serve with both types of pears on the side.