Once the cake has cooled completely, using your hands, break the cake into small crumbs. You can also use a stand mixer by putting medium sized chunks of cake into the bowl and with the paddle attachment, mix until small crumbs form.
Add in ½ cup frosting and mix (with your hands or with the mixer). You have achieved the right consistency when the cake looks moist and if you roll a ball in your hands, it keeps its shape. Add more frosting if the cake appears to be dry and doesn’t stick together.
To roll the balls, use a small cookie or ice cream scoop and scoop the cake and frosting mixture making sure to level off the scoop to ensure that all the balls are equal in size. Gently roll the ball between your hands until it is smooth and spherical. Place on a baking tray, cover, and put in the refrigerator for several hours to firm up.
Place chocolate into a medium heat proof bowl. Microwave in 30 second intervals until melted and smooth. Drop the cold cake ball into the melted chocolate. Using a small spoon, coat the ball completely.
Scoop the ball out with the spoon, and gently tap the spoon on the side of the bowl to remove any excess chocolate. Gently place onto a cookie sheet lined with parchment paper. You may need to use a toothpick or skewer to help gently release the cake ball off the spoon.
Once all the balls have been coated, place leftover melted chocolate into a small piping bag or zip lock bag. Cut a very small opening at the tip and drizzle over the chocolate-coated cake balls in a side-to-side pattern. Leave at room temperature until chocolate has hardened.
Serve or store in airtight container in the refrigerator for up to 3 days