In a medium saucepan, combine raspberries and water. Bring to a simmer, mashing gently. Strain to collect juice and stir in sugar and lemon juice, then chill.

In a large mixing bowl, whisk heavy cream until stiff peaks form. Set aside.

In another bowl, mix mascarpone cheese, sugar, and chilled raspberry syrup. Fold in whipped cream gently.

Dip ladyfingers quickly in raspberry syrup and layer in a 9x9 dish. Add half of the mascarpone filling and half of grated white chocolate.

Repeat layers with remaining ingredients and cover securely.

Chill for at least 6 hours or overnight for best results.