In the bowl of a stand mixer fitted with the paddle attachment, beat mascarpone at medium speed until creamy. Add confectioners’ sugar, 1 cup (120 grams) at a time, beating until smooth. Add crème fraîche, vanilla, and salt, beating to combine.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/berry-buttermilk-cake-mascarpone-creme-fraiche/