For a lighter version of this dish, substitute half of the cream for Greek yogurt.
In a bowl, whisk together the egg yolks and 6 tablespoons of the sugar until pale and fluffy, and set aside.
In a small bowl, mix the cornflour to a paste in 1 to 2 teaspoons of the milk. Put the cornflour paste, the remaining milk, and the ground almonds into a pan, and bring to a boil over a low heat. Boil for 1 to 2 minutes, take off the heat, and then gradually add the egg and sugar mixture a little at a time, whisking continuously.
Return the mixture to a simmer and cook, whisking continuously, for 4 to 5 minutes, or until the mixture has thickened enough to coat the back of a spoon. Pour the mixture into a bowl and cover with plastic wrap. Set the mixture aside to cool.
Heat a dry frying pan over low heat, and add the porridge oats, and toast, stirring regularly, for 4 to 5 minutes, or until golden brown. Set aside to cool, and then chill in the refrigerator for at least 10 minutes.
In a food processor, blend a handful of the blackberries, the lemon juice, and the remaining sugar to a puree. Stir in the remaining blackberries until well combined.
Add 1 tablespoonful of the whipped cream to the reserved milk and almond mixture, and stir until well combined. Fold in the remaining whipped cream, the cooled porridge oats, and the whisky.
To serve, spoon layers of the almond cream mixture into 4 or 5 serving glasses, then spoon over layers of the blackberry puree, and then sprinkle over a layer of the flaked almonds. Repeat the process to create more layers until all of the ingredients have been used up. Garnish with any remaining flaked almonds, and sprinkle with icing sugar.