Step 1, In a medium saucepan, combine brown sugar, cocoa and flour. Stir in water, a little at a time, to make a smooth paste. Stir in milk and butter. Bring to a boil over medium heat and let boil 5 minutes. Remove from heat and stir in vanilla. Let cool completely at room temperature, stirring often to prevent a skin from forming. Store in refrigerator after cooling. read more