Ingredients

1/2 cup (1 stick) butter, softened
1 cup packed dark brown sugar
1/3 cup heavy cream, plus more as necessary
1 tablespoon pure vanilla extract
1 16-ounce box confectioner’s sugar
2 cups finely chopped black walnuts, for garnish (optional)

Directions

Melt butter in saucepan.  Add brown sugar and cream.  Cook over medium-low heat for about 2 minutes, until the sugar is dissolved.  Remove from heat and add vanilla. Transfer to a large bowl.

Using a handheld electric mixer, beat in confectioners’ sugar until smooth.  If frosting is too thick, add 1 tablespoon heavy cream at a time until consistency is right.