Whisk together 6 Tbs. unsweetened cocoa powder, 6 Tbs. sugar, and 1/2 tsp. Kosher salt in a bowl. Heat 4 1/2 cups milk or a non-dairy alternative in a medium saucepan over medium-low heat until bubbly around sides of pan. Whisk in cocoa mixture. Divide among six cups. Cut marshmallows in half and press Wilton Red Vein Candy Eyeballs into the sticky sides. Top cocoa with eyeballs.
In a microwave heat 3/4 cup milk in glass cup for 45 seconds or until bubbly and whisk in 2 Tbs cocoa mixture.