In a small pan, add milk, butter, and brown sugar. Cook on low-medium heat while occasionally stirring.
Cook until bubbles form. Turn off the stove. Let the mixture cool for about 15-20 minutes. You need to make sure you do this otherwise you'll end up with liquid frosting which will look more like a glaze.
In the meantime, chop the pecans.
Pour the cooled brown sugar mixture over 1 cup of powdered sugar.
Use an electric mixer to prepare the frosting.
Add another 1/2 - 3/4 cup of powdered sugar so the frosting isn't as liquidy.
Beat the mixture for another minute.
Add vanilla. Beat for another minute.
Add chopped pecans. Mix for a few seconds.
Pour the frosting over the cooled chocolate cake. My frosting was slightly