Prepare the Raspberry Layer:
In a saucepan, combine raspberries, sugar, and lemon juice.
Cook over medium heat until the raspberries soften and release their juices.
Let cool slightly, then strain to remove seeds (optional).
Make the White Chocolate Mousse:
Melt the white chocolate in a microwave-safe bowl in 30-second increments, stirring between each, until smooth. Let cool slightly.
In a separate bowl, whip the heavy cream, vanilla extract, and sugar until stiff peaks form.
Gently fold the melted white chocolate into the whipped cream until well combined.
Assemble the Mousse:
Spoon a layer of 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.
Chill and Garnish:
Refrigerate the mousses for at least 30 minutes to set.
Just before serving, garnish with fresh raspberries and white chocolate shavings.