In the bowl of a stand mixer fitted with the whisk attachment, beat mascarpone, confectioners’ sugar, salt, and vanilla at medium speed until well combined, 1 to 2 minutes. With mixer on low speed, add cream in a slow, steady stream, beating until well combined; scrape sides of bowl. Beat at high speed until mixture is whipped and fluffy, 1 to 2 minutes. Cover and refrigerate for up to 3 days; stir before using.