Melt butter in a saucepan over medium heat. Be careful not to burn the butter. Take the butter off the iron and stir in confectioners’ sugar and vanilla until smooth. You can add more sugar to thicken the glaze. Stir in hot water one tablespoon at a time until the icing is thin, but not watery.
To avoid a greasy taste, heat the oil up on medium high for five minutes, and then gently reduce the heat until thermometer reads 350℉ (175℃).
