Penuche is really candy. It came from Mexico.
In saucepan melt
1/2 cup butter
1 cup brown sugar (packed)
Continue cooking over low heat for 2 minutes, stirring.
1/4 cup milk
Bring to a full rolling boil, stirring constantly.
Take out spoon and set pan in cold water. When you can hold your hand on the bottom of the pan the syrup is cool enough.
Then stir in
1 3/4 to 2 cups sifted confectioners' sugar
Set pan in ice water. Beat until thick enough to spread. If icing is too thin, add more confectioners' sugar. If too thick, add a few drops of hot water.
Well-packed brown sugar will hold its shape when turned out of the cup.
A full rolling boil looks like this.