Combine sugar, white wine and lemon juice and bring to a boil. Slit vanilla pod lengthwise and add to the pot. Rinse and halve pears and add to the syrup, poach for about 5 minutes. Remove pears with a slotted spoon and simmer syrup until it thickens slightly.
Butter baking pan. Roll out dough and line baking pan with it, making small edge all around. Mix eggs with mascarpone and vanilla sugar and spread on the dough. Top with pears and bake in preheated oven at 200°C (gas mark 3-4, fan 180°C) (approximately 400°F) for about 20-25 minutes. Drizzle pears with the syrup 5 minutes before the end of baking. Remove from the oven and serve warm or cold.