Put the frozen blackberries in a hot pan, add 3 tablespoons of pisco, turn the heat to low, and add a tablespoon of sugar.
Wait until the water has evaporated and stir.
The blackberry sauce should look like a coulis.
Dilute the gelatin into 1.7 fl oz (3 1/3 tbsp) of boiling water, stir and wait until it is warm. Beat the Chantilly cream with sugar (add a teaspoon of vanilla extract if you wish). Then mix with the gelatin. Mix the milk with one teaspoon of vanilla extract. Quickly soak the cookies in milk.
Put the split cookies on the base, add some blackberry and whipped cream mixture, and continue the sequence until topping with cream. Decorate with the blackberry coulis and a mint leaf.
