add 1/3 cup sugar (use less if using sweetened, frozen berries) and a squeeze of lemon juice and blend.
In a separate bowl, with an electric mixer or whisk, beat the cream, add the remaining 1/3 cups sugar gradually as the cream whips, until it holds a peak when the beater (or whisk) is lifted from the bowl.
Blend in the puree.
spoon into individual glasses and chill or freeze.
add some chocolate shavings, berries or whipped cream. (optional)