Place the Chocolate in a Microwave safe bowl, and melt until smooth and creamy.
Stir well, and spoon or ladle into the molds, making sure to coat the inside of the molds. Pour excess chocolate back into the bowl, and place the molds in the refrigerator, and let harden for 15 minutes.
Remove molds from refrigerator, and carefully remove chocolate from molds, placing 6 half balls in a row. These will be the bottom parts, or half of the Cocoa bombs.
Heat a non stick Skillet, on low, and place one half ball with the open side down, melting just the edges, remove, place on a cookie sheet, and fill the Ball with the powdered Cocoa, Rum Chata, and mini Marshmallows. Repeat, until all 6 Balls are done.
Place the other half of the Chocolate balls in the skillet, with the open side down, and melt just the edges of the ball. Remove from the Skillet, and immediately place on one of the chocolate balls, filled with the cocoa, etc., making the top of the ball/bomb. Hold in place a few seconds to make sure the top and bottom are melted together.
When all the Cocoa Bombs have been filled, and melted together, place them in the refrigerator for 30 minutes, until chocolate is completely set. Remove from the Refrigerator, and sit the cookie sheet on the counter.
Place White Chocolate, and Milk Chocolate in separate microwave safe bowls, and microwave at 15 second intervals until the chocolate melts. Stir well, and place the melted chocolate - white and milk - in a Pastry bag, and pipe the White Chocolate and milk chocolate over the Cocoa Bombs (see photo) and sprinkle with your favorite Sprinkle mix. Place one Hot Cocoa Bomb in the bottom of a large mug, and pour heated milk over the top. Cocoa Bomb will melt and bubble, and marshmallows will float to the top. Stir the powdered cocoa, and Enjoy!