1. In a small saucepan, combine the raspberries, sugar, and 2 tablespoons of water. Cook over medium heat, stirring occasionally, until the raspberries break down and the mixture thickens, about 5 minutes. Add raspberry liqueur if using. Let it cool completely.
2. In a large bowl, whip the heavy cream until it forms soft peaks. Add the mascarpone cheese, melted white chocolate, and vanilla extract, and gently fold until smooth and creamy.
3. Dip each ladyfinger into the raspberry mixture, making sure they are well coated but not soggy.
4. In a 9×9-inch dish, arrange a layer of soaked ladyfingers. Spread half of the mascarpone mixture over the ladyfingers. Repeat with another layer of soaked ladyfingers and the remaining mascarpone mixture.
5. Cover and refrigerate for at least 4 hours, or overnight for best results. This allows the flavors to meld together beautifully.
6. Before serving, garnish with additional raspberries and white chocolate shavings.

Pro Tip: When melting the white chocolate, use a microwave at 50% power in 30-second intervals to prevent burning, stirring each time until smooth.