Soak gelatine in cold water. Mix buttermilk, citrus juice and sugar. Squeeze the gelatine, dissolve it and mix with 3 tablespoons of buttermilk mix. Then stir into the remaining buttermilk and chill for about 20 minutes. Put lemon cookies into a freezer bag and crumble them with a cake roll. Melt the butter and stir in the cookie crumbs. Draw a circle (17 cm Ø) in pudding tin size on a baking paper.
Fill the circle with the mixture, press flat and chill. Stir the buttermilk mixture again with a whisk. Whip the cream until stiff and fold into the buttermilk. Rinse the pudding mould (1.7 litres capacity) with cold water, fill in the cream and chill for at least 4 hours, preferably overnight. Place the mould briefly in hot water and turn over onto the biscuit base. Decorate with lemon and lime peel spirals