Preheat the oven to 180°C, fan 160°C, gas mark 4.
Roll out the pastry and use to line a 23cm tart tin. Chill in the fridge for 10 minutes.
Place the tin on a baking sheet, line the pastry case with greaseproof paper and fill with baking beans (or uncooked rice). Bake in the oven for 15 minutes, then remove the beans or rice and cook for a further 5 minutes, until just golden.
Meanwhile, whisk together the butter, sugar and almond essence, then slowly add in the beaten eggs. Fold in the almonds, flour and most of the pistachios (reserving some for a garnish), and spoon into the tart case.
Arrange the peach slices in concentric circles on top of the almond mixture then bake for 40-45 minutes, until golden.
Slice and serve with the ice cream. Finely chop the reserved pistachios and sprinkle over the top.
Cook's tip: Don't panic if you haven't got a tart tin, you can buy one from our Sainsbury's baking range.