In a saucepan, combine raspberries, sugar, and lemon juice. Cook over medium heat until the raspberries break down and the mixture thickens slightly. Let it cool and then strain to remove seeds, if desired.

Melt the white chocolate in a heatproof bowl set in the microwave for about 60 seconds, stirring occasionally. Once melted let it cool slightly. In a separate bowl, whip the heavy cream, vanilla extract, and sugar until stiff peaks form. Gently fold in the melted white chocolate into the whipped cream until well combined.

Spoon a layer of the raspberry sauce into the bottom of each glass. Carefully spoon or pipe the white chocolate mousse over the raspberry layer, filling the glasses. Repeat the layers if desired or if your glasses are tall.

Refrigerate the mousses for at least 30 minutes to set. Just before serving, garnish with fresh raspberries and white chocolate shavings for a touch of elegance.