Mix milk and brown sugar
Cook on medium heat for about 10 minutes.
Bring these ingredients to a boil, stirring constantly with a whip so that it does not curdle. Continue this until it appears to be caramelized.
Let cool ’til just warm, then mix in:
½ cup butter
2 cups icing sugar
1 tsp vanilla
Spread on cake (or take a teaspoon and eat directly from the bowl 🙂