Place your saucepan onto your burner and turn the heat to medium/high.
Add your butter and stir. Allow it to melt, then add your brown sugar and stir. Then add milk.
Mix to make sure that the brown sugar dissolves. Once you see steam coming up from the milk add your powdered sugar and vanilla.
Mix these in to dissolve and blend, then turn your heat to medium.
Allow this to cook for 40-45 minutes. Stir every 5 minutes. If you notice slight burning at the bottom, turn your heat a little lower.
After it's cooked down and thickened, pour it into a glass jar. Allow it to cool for 10 minutes. Then drizzle where you want it.
