In the bowl of a stand mixer fitted with the paddle attachment, beat butter and salt at medium speed until smooth and creamy, about 3 minutes. With mixer on low speed, gradually add confectioners’ sugar, beating until combined and stopping to scrape bottom and sides of bowl. Beat in Peanut Chocolate Spread and vanilla. Increase mixer speed to high, and beat until pale and fluffy, 1 to 2 minutes. Use immediately.