In a large bowl, beat together butter and salt with a mixer at medium speed until smooth and creamy, 1 to 2 minutes, stopping to scrape down sides of bowl.
With mixer at low speed, gradually add confectioners’ sugar to butter mixture, alternately with 2 tablespoons preserves at a time, beginning and ending with confectioners’ sugar and beating until smooth after each addition. Increase speed to medium, and beat until buttercream is light and fluffy, 1 to 2 minutes, stopping to scrape down sides of bowl as needed. Use immediately.
Notes
*We used Kerrygold.
Recipe by TeaTime Magazine at https://teatimemagazine.com/brownies-with-plum-buttercream-recipe/