Blend sweetened condensed milk, evaporated milk, cream, and cocoa in a blender until completely smooth. Sprinkle gelatin over water in a small saucepan; let stand for 5 minutes to soften. Place gelatin mixture over low heat and stir until gelatin is dissolved; pour mixture into blender and pulse several times to combine.
Pour gelatin mixture into preferred gelatin mold; chill until set, 1 to 1 1/2 hours. Unmold and serve.