In a mixing bowl, combine the butter and the flour and rub between the fingertips until it resembles fine breadcrumbs. Add the sugar and salt and mix well, then add up to 3 tablespoons of water to bring the mixture together into a ball. Wrap in cling film and chill in the fridge for 30 minutes.
Preheat the oven to 200 C / Gas 6. Line a baking tray with baking parchment.
Remove the pastry from the fridge and turn out onto a lightly floured work surface and using a rolling pin, roll out into a circle. Place onto the prepared baking tray.
For the filling:
Cover with jam, leaving a 3cm edge then sprinkle with ground almonds. Layer the pears in a circle then fold in the pastry edges and sprinkle all over with sugar.
Bake in the preheated oven for 45 minutes or until the filling is hot through and the pastry is golden brown. Remove from the oven, slice and serve warm.