Crush the shortbread cookies. Add the melted butter and mix well. Press the mixture firmly into the bottom of a springform pan or cake ring. Chill in the refrigerator.

Heat the juice of 1 1/2 lemons. Add the rehydrated and drained gelatin sheets. Pour this lemon mixture into 200 grams (about 3/4 cup) of Philadelphia cream cheese. Mix well.

In a separate bowl, mix 100 grams (about 1/3 cup) of Philadelphia cream cheese with the blackberry jam.

Whip the heavy cream until stiff peaks form. Fold 2/3 of the whipped cream into the lemon mixture, then add the lemon zest. Fold the remaining 1/3 of the whipped cream into the blackberry mixture.

Pour the blackberry mixture over the cookie crust and smooth the surface. Then pour the lemon mixture on top and smooth again. Refrigerate overnight.