Mix the flour and salt in a bowl. Add the butter and rub together using your hands to form an even, crumbly mixture. Pour in the water and mix quickly to form a soft dough; do not knead. Flatten the dough, cover and chill for approx. 30 mins.
Combine the mixed seeds, fleur de sel, rosemary and pepper.
On a lightly floured surface, roll out the pastry to approx. 0.5 cm thick, place on a baking tray lined with baking paper. Spread the cheese over the pastry, leaving a border of approx. 5 cm. Arrange the apples and shallots on top of the cheese. Fold the edges inwards, sprinkle with the seed mix.
Approx. 25 mins. in the lower half of an oven preheated to 220°C.