In a medium saucepan, combine raspberries and water. Cook for 5-7 minutes, then strain and return the juice to the saucepan. Add sugar and lemon juice, simmer for another 5 minutes. Let cool.

In a large bowl, beat heavy cream until stiff peaks form, about 3-5 minutes. Set aside.

In a stand mixer, blend mascarpone, sugar, and cooled raspberry syrup until smooth. Carefully fold in whipped cream.

Dip ladyfingers in raspberry syrup for 1-2 seconds and arrange in an 8-inch square dish. Spread half of the mascarpone filling over them and top with grated white chocolate.

Repeat layers with remaining ladyfingers and mascarpone, topping with the rest of the white chocolate. Chill for at least 6 hours, preferably overnight.