In a heatproof bowl placed over a pot of boiling water (or in a double boiler), combine the heavy cream, sugar and cornstarch and heat, stirring often, until the sugar has completely dissolved.
Remove the mixture from heat and allow to cool. Whisk in the sour cream and vanilla and chill. Serve with mixed berries.
Recipe by Zoom Yummy - Crochet, Food, Photography at https://zoomyummy.com/2016/04/18/swedish-cream-berries/