How to Make It
In a small saucepan, mash the 1 cup of blueberries with the sugar and salt and bring to a simmer over moderate heat. Cook, stirring, until jammy, about 10 minutes. Remove from the heat and scrape the jam into a food processor. Let cool completely.
Add the sour cream and cream cheese to the food processor and puree with the jam until smooth. In a large bowl, beat the heavy cream to soft peaks. Fold in the berry cream until blended. Spoon the mousse into glasses and sprinkle with chopped pistachios and blueberries.