For the shortbread stack, pre-heat the oven to 180C/350F/Gas 4.
Sift the icing sugar, flour and cornflour together into a bowl and add the ground almonds.
Using your fingers, rub or mix the butter in until there are no visible lumps of butter.
Turn the mixture out onto a lightly floured surface and knead a few times, to just form a smooth dough.
Roll the dough out, about 3mm/1/8in thick and cut out 12 rounds, 7.5cm/3in diameter. Place on a baking tray and bake until they are a light golden-brown, about 8-12 minutes.
Remove them from the oven and cool completely.
For the filling, place the double cream into a bowl and whisk to soft peaks, then fold in the custard and whisk until it just holds a peak.
Fold in the chopped strawberries.
Place half the raspberries into a food processor with the icing sugar and blitz to a puree.
Pass through a fine sieve into a bowl, then check the sweetness level and adjust accordingly.
To assemble, place one disc of shortbread into the centre of the plate and top with a spoonful of cream mixture.
Place raspberries around the edge of the shortbread to fill tightly, enclosing the cream in the centre.
Top with another shortbread disc and repeat with the cream and raspberries.
Top with one more disc, then dust with icing sugar and finish with a sprig of mint.
Spoon a little of the raspberry sauce around the edge.