Melt the butter in a saucepan over low heat. Chop the biscuits, put them in a bowl and then pour the butter and mix until you get a homogeneous composition. Put a form with removable walls (or an adjustable cake ring) on a plate (diameter 20 cm) and pour the composition of biscuits, then compact it with a glass with a straight bottom. Put the top in the fridge and in the meantime prepare the blackberry cream.
Put the blackberries to boil and let them boil for 5 minutes, then mix them and put them in a strainer to get rid of the seeds. Let the blackberry sauce cool.
To prepare the 2 creams, mix in 2 pots the mascarpone cream with the ground sugar and then add in each 125ml of mixed liquid cream. In one bowl add 125 ml of blackberry syrup and in the other bowl add the yogurt and mix until the composition is homogeneous.
Put the hydrated gelatin in cold water for 10 minutes (in 2 different pots), then melt it on a steam bath and let it cool. Add a few tablespoons of blackberry cream over the gelatin and then pour over the entire cream and mix until smooth. Do the same with the yogurt cream.
Pour 3 tablespoons of yogurt cream over the cookie sheet and then add 3 tablespoons of blackberry cream and so on until you finish the whole composition, then cool the cake.
After 2-3 hours (or better leave overnight), when the cream has hardened, remove the cake ring. Before undoing the cake ring, carefully pass it around with a knife to peel off the edges.
Decorate the cake with blackberries.