In a large mixing bowl, combine the heavy whipping cream, powdered sugar, and vanilla extract. Using an electric mixer, whip the mixture on medium-high speed until soft peaks form, about 3-5 minutes.
Gently fold in the raspberry puree into the whipped cream until well combined, creating a marbled effect.
In serving glasses, add a few ice cubes and pour in the lemonade until the glass is about three-quarters full.
Spoon the whipped raspberry cream mixture on top of the lemonade in each glass.
Garnish with fresh raspberries and lemon slices. Serve immediately with a straw or spoon.