In a saucepan, mix together the raspberries, sugar, and lemon juice. Heat over medium heat until the raspberries soften and the mixture thickens a bit.
Allow the mixture to cool, then strain it to remove the seeds if you prefer.
White Chocolate Mousse
Place the white chocolate in a heatproof bowl and melt it in the microwave for about 60 seconds, stirring every so often. Allow it to cool slightly afterward.
In another bowl, beat the heavy cream, vanilla extract, and sugar until stiff peaks form.
Carefully fold the melted white chocolate into the whipped cream until fully incorporated.
Assemble
Add a layer of raspberry sauce to the bottom of each glass using a spoon.
Gently spoon or pipe the white chocolate mousse over the raspberry layer, filling each glass.
If using tall glasses or if desired, repeat the layers.
Chill and Garnish
Chill the mousses in the refrigerator for at least 30 minutes to allow them to set.
Before serving, top with fresh raspberries and white chocolate shavings for a polished touch.