Mix the flour, salt and sugar 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.
Quarter the dough, shape into balls, press into the prepared tart tins, prick the base firmly with a fork, chill for approx. 30 mins.
Transfer the cheese mixture to the prepared tart tins.
Using the whisk on a hand mixer, whisk the cheese, crème fraîche and eggs in a bowl until the mixture becomes lighter in colour. Stir in the milk, dates and onions, season.
Approx. 35 mins. in the lower half of an oven preheated to 180°C.