Preheat the oven to 200°C/400°F/Gas 6 and place a baking tray in the oven. On a lightly floured surface, roll the pastry into a square large enough to line a buttered 900ml (1½ pint) shallow pie dish
Transfer the pastry to the pie dish and trim off any excess. Knock up the pastry edge with a knife so the pastry layers rise well during baking. Brush the base of the pastry case with the jam and chill while making the filling
In a large bowl, beat the almonds with the sugar, butter, eggs and almond essence. Remove the case from the fridge and spoon the mixture on top of the jam. Smooth the top
Place the tart on the hot baking tray and bake in the oven for 30-35 minutes, until the filling has set. Serve hot with custard or cold with cream