Once the cake is cooled, use your hands or two forks and to crumble the cake into fine crumbs.
In a large bowl, mix crumbs with 1/4 cup + 1 tablespoon buttercream, 1/4 teaspoon of mint extract and 1/4 cup mini chocolate chips.
Mix with hands or a fork until buttercream is fully incorporated. You want the mixture to be just moist enough to roll into balls.
Using a small ice cream scoop, scoop out a small amount of cake mixture and roll between cupped hands until you reach the desired round shape.
Put balls on a plate and cover with plastic wrap. Place in refrigerator for at least 2 hours.
Place dark chocolate melting chocolate in a microwave safe bowl. (Make sure it is deep enough to submerge the entire ball in the chocolate). Microwave the chocolate in 30 second increments, stirring after each heating, until it is melted.
Dip lollipop stick into chocolate and then into the middle of a cake ball.
Dip cake ball into the chocolate until it is completely covered. Hold it sideways over the bowl and rotate it and tap it so the excess chocolate comes off.
When the excess chocolate has dripped off, push the lollipop stick into styrofoam block to dry.
Once chocolate is dry, melt green chocolate in microwave safe bowl.
Place melted chocolate in pipping bag, with a small round tip.
Over the bowl of green chocolate, drizzle lines covering all sides of the ball. Place back in the styrofoam block to dry.