Chocolate Silk Frosting 

1 can evaporated milk
6 tbsp. sugar
1/4 cup unsweetened cocoa
2/3 cup whole milk
1 egg, lightly beaten
2 tbsp. corn starch
1 tsp. unflavored gelatin
2 tsp. vanilla 

In heavy saucepan combine sugar, cocoa, cornstarch and gelatin. Whisk in the milks until just blended. Set pan over medium heat and cook, whisking constantly, until mixture just boils, is thickened and smooth.  In small bowl, whisk egg until blended. Whisk a small amount of the hot mixture into egg then stir the mixture back into the remaining hot mixture in pan. Cook, stirring constantly 3 to 4 minutes. Do not boil.  Remove from heat and stir in vanilla. Cover and cool in sink filled with ice water.