Place the butter in a bowl, whisk in the sugar and salt using the whisk attachment on a hand mixer. Whisk in the egg and vanilla. Add the flour, mix quickly to form a soft pastry dough – do not knead. Flatten the dough, cover and chill for approx. 30 mins. On a lightly floured surface, roll out the pastry into a circle (approx. 32 cm in diameter), place in the prepared tin, chill for another 15 mins.
Approx. 15 mins. in the centre of an oven preheated to 200°C. Remove from the oven, reduce the heat to 180°C.
Scatter the almonds over the base.
Beat the egg whites with the salt until stiff. Gradually add the sugar and continue beating until the egg whites turn glossy. Carefully fold in the almonds and berries. Spread the mixture over the base.
Approx. 25 mins. in the centre of the oven. Remove the cake from the oven, allow to cool slightly, slide onto a cooling rack and leave to cool completely.