For the pears, add the red wine, spices, caster sugar and orange to a saucepan and warm gently. Place the pears in the saucepan and bring to the boil, reduce to a simmer and cook for 15 minutes, or until the pears are tender.
Remove the pears and pat dry using kitchen paper. To decorate the pears (optional), place the halves cut-side down and use a sharp knife to make 5-6 cuts widthways, about 1cm/½in deep and 5mm wide. Leave to cool.
For the sweet pastry, add the flour, icing sugar and butter to a blender. Blend until the mixture resembles breadcrumbs. Add the egg yolk and pulse briefly. Pour in just enough ice cold water to bring the mixture together as a ball in the blender. Remove and place onto a lightly floured surface. Knead just enough to form a ball, wrap in cling film and place in the fridge for 15-20 minutes.
Remove the dough from the fridge and set aside a small piece of the dough. On a lightly floured work surface, roll out the remaining dough to a circle and line a 23cm/9in flan tin. Use the reserved dough to push the dough into the fluted sides. Prick the base with a fork and leave in the fridge for 15 minutes.
For the frangipane, beat the butter and sugar using a an electric mixer until light and fluffy. Beat in the eggs one at a time then beat in the ground almonds and essence.
Preheat the oven to 220C/200C Fan/Gas 7. Line the pastry case with baking parchment and fill with baking beans or uncooked rice. Bake for 10 minutes, then remove the baking beans and baking paper and return to the oven for a further 5 minutes, or until the pastry is dry.
Reduce the oven temperature to 180C/160C Fan/Gas 4.
For the topping, sprinkle a handful of ground almonds on the base of the pastry case. Spoon the frangipane into the pastry case. Add the pears, cut-side down in a star pattern. Press them gently into the frangipane and sprinkle the sliced almonds between the pears.
Bake for 45 minutes, or until the crust is golden-brown and the frangipane firm to the touch. Remove from the oven and brush all over with the apricot jam.
For the icing, mix the icing sugar with the lemon juice until you have a smooth paste that drizzles from a spoon. Add a little water if the icing is too thick.
Cool on a wire rack for 5-10 minutes before removing the tart casing. When cool, drizzle the icing all over and serve warm or cold.