Place Crema Mexicana, a stainless steel bowl and the beaters of your hand mixer in freezer for 30 minutes before preparation. Whip the Crema Mexicana with a hand mixer until light and fluffy. Slowly incorporate the cocoa powder and sweetener. Pour into you favorite freezer safe glasses. Chill in freezer for 20 minutes.Remove and let "thaw" for 10 minutes before serving.