Grease a 23cm/9in tart tin. To make the pastry, place the flour, almonds, sugar and butter in a food processor and pulse until the mixture resembles breadcrumbs. Slowly add the beaten egg and bring the mixture together to make a dough. Wrap the dough in cling film and chill for at least one hour.
Unwrap the pastry and roll out on a lightly floured surface. Line the tin with the pastry, prick all over with a fork and refrigerate for two hours, or freeze for at least 30 minutes.
Meanwhile, preheat the oven to 200C/400F/Gas 6. Line the pastry case with greaseproof paper and add baking beans then bake blind for 15-20 minutes. Remove the greaseproof paper and baking beans and let the tart case cool for about 10 minutes. Reduce the oven temperature to 160C/312F/Gas 2½.
Grate the fudge into the bowl of a food processor using the grating disc. Replace the grating disc with the mixing blade, add the cheese, eggs and double cream and blend well.
Score the nectarines with three light cuts horizontally and vertically and place in the pastry case skin side up. Pour in the filling and bake in the centre of the oven for 20 minutes or until the mixture is just set. Remove the tart from the oven and leave to rest for 30 minutes before serving.