In a large chilled bowl, beat the heavy cream on high speed until a peak has formed (about 3-5 minutes). Once a peak forms, slowly add in the chocolate milk with the beaters still running.
Fold in the sweetened condensed milk, cocoa powder and any mix in's.
Pour into a 9x9" pan or 2 quart container. Freeze until set (about 4 to 5 hours). Allow to soften slightly on the counter. Scoop and serve!
Notes
Storage: I like to freeze it in a bread loaf pan for easy scooping. Cover tightly with plastic wrap and store near the back of the freezer to prevent freezer burn. It will keep up to 3 months.