Prepare the tin
Line a spring form tin (24 cm diameter) with baking paper, grease the rim.
Peel and core the pears and chop into pieces. Simmer the pears, lemon juice and water, covered, over a low heat, for approx. 10 mins. until soft, puree, leave to cool.
Mix the butter, sugar and salt in a bowl. Add the eggs and continue to stir until the mixture becomes paler in colour.
Grate in the lemon zest, pear puree and nuts.
Mix the flour and baking powder, mix into the dough and transfer to the prepared tin.
For the topping, peel and core the pears, halve them and slice into them very finely, so that they don't fall apart, then arrange on the dough. Sprinkle over the sugar.
for approx. 1 hr. in the lower half of an oven preheated to 180°C. Remove from the oven, allow to cool slightly, remove from the tin, place on a cooling rack and allow to cool completely.
Heat the apricot jam and water in a small pan and coat the pear tart with the mixture.