Make the puree by mixing together the defrosted berries and icing sugar and allow to sit for 30 minutes. When ready, press through a sieve and reserve the pulp thatis left in the sieve into another bowl. Place ricotta in a sieve over a bowl and let drain for 1 hour. Line an 8inch spring form pan with non stick paper. Butter the sides, bottom and rim of pan. Mix the biscuit crumbs with 1 teaspoon of the sugar and coat the pan. Spoon the extra crumbs onto the bottom of the pan. Place the mascarpone into a food processor and pulse till smooth. Add in the ricotta and pulse again. Add in the eggs, followed by the sugar, lemon zest and juice and pulse till smooth. Pour the mixture into the prepared tin. Spoon in the reserved raspberry pulp and swirl around with a spoon. Place the tin into a larger deep oven dish, will with boiling water and bake in the oven at 350`f for 1 hour and 15 to 30 minutes. Remove the cheesecake from the oven and allow to cool down completely before serving with the fruit puree and fresh berries.