In a small saucepan, heat 1/4 cup of the heavy whipping cream until it just simmers. Pour it over the chopped sugar-free white chocolate in a bowl and let it sit for 1 minute. Stir until completely smooth and let cool to room temperature, about 15 minutes.
In a separate bowl, combine the fresh raspberries, granulated erythritol, and lemon juice. Mash roughly with a fork, leaving some chunks for texture. Set aside.
Beat the softened cream cheese and powdered erythritol together until smooth and fluffy. Add the cooled white chocolate mixture and vanilla extract, beating until perfectly combined.
In a large chilled bowl, whip the remaining 1 3/4 cups of heavy whipping cream until stiff peaks form. Fold the whipped cream into the white chocolate cream cheese mixture in three additions, folding gently each time to keep it light and airy.
Spoon a small layer of mousse into the bottom of 6 serving glasses or cups. Add a spoonful of the raspberry mixture on top. Repeat the layers one more time, finishing with a generous layer of mousse.
Refrigerate for at least 2 hours until set. Top each cup with a few fresh raspberries and a sprinkle of crushed freeze-dried raspberries just before serving.