Method:
To make the pastry, place the flour and caster sugar in a large bowl and rub in the butter until the mixture looks like breadcrumbs. Add the eggs and stir in, then use your hands to bring the pastry together into a ball. Wrap in cling film and set aside in the fridge to chill for 30 minutes
For the filling, place the gooseberries and elderflower cordial in a solid steam container and cook for two minutes at 100C until the gooseberries are just tender and still holding shape. Pour the gooseberries into a sieve with a bowl underneath to catch the juice. Reserve the juice and allow the gooseberries to cool. If a Miele Steam Oven is not available, place the gooseberries and cordial in a saucepan and cook on a low heat for 3 – 4 minutes.
On a floured surface, roll out the pastry and use it to line a 25cm diameter, loose-bottomed, deep flan tin. Spread the cooled gooseberries across the pastry base. Whisk together the eggs, egg yolks, milk, double cream and sugar and add in a generous grating of nutmeg. Carefully pour this custard over the gooseberries into the flan case.
Transfer the tart to an oven, on the highest shelf at 160C for 30 – 35 minutes until the pastry is cooked and the custard is just set. If using a Miele oven, bake using the Intensive Bake function. It should still have a slight wobble in the centre. Allow to cool and then chill overnight in the fridge.
Pour the reserved juice into a small saucepan and add the elderflower cordial and caster sugar.
Bring up to the boil and simmer gently to create a slightly thickened syrup. Taste to check whether a little more sugar is required. Set aside and allow to cool. Serve the tart with the sauce on the side.