Mix the flour, sugar 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 into a pastry dough; do not knead. Press 3/4 of the pastry into the prepared tin, creating a rim of approx. 3 cm. Chill the tin and the remainder of the pastry separately for approx. 30 mins.
To blind bake
Cover the pastry base with baking paper, weigh down with dried pulses. Bake for approx. 15 mins. in the lower half of an oven preheated to 180°C. Remove from the oven, allow to cool slightly, remove the dried pulses and baking paper.
Using the whisk on a hand mixer, beat the butter and icing sugar for approx. 5 mins. Stir in the almonds, vanilla seeds and egg. Spread the filling over the blind-baked tart base, top with the berries, press down gently. Rub the remainder of the pastry dough and the almonds by hand to form a crumbly mixture.
Approx. 45 mins. in the lower half of an oven preheated to 180°C. Remove from the oven, allow the tart to cool slightly, remove from the tin and leave to cool completely on a rack. Cut into 10 slices.