In a large mixing bowl, combine your butter and cream cheese until well mixed and fluffy. Add in vanilla and peppermint extract (if using).
Add in a few drops of green food coloring until the desired hue is reached. Remember that your color will lighten when you add in powdered sugar.
Add in salt (optional) and powdered sugar about 1/2 cup at a time, until you reach your desired consistency. 3 1/2 cups might be enough for some, depending on your butter and cream cheese, while some may need the entire 4 cups (or even a tad more). You want a very thick frosting - much thicker than what you'd frost a cake with, but still able to stir.
Add in your chocolate chips.
If needed add in a drop or two more food coloring. Stir until well combined.
Place mixture in refrigerator for at least two hours.
Once chilled use a spoon or small scoop to create balls of frosting, and place them on a baking sheet (that will fit in your freezer) lined with wax or parchment paper. Depending on the size of your balls (I made mine about 1-1 1/2" in diameter) you should get about 24 balls.
Once all the balls have been made, place in the freezer for at least two hours.
Prepare your chocolate coating according to package directions. Make sure it's not too hot prior to dipping.
Take your frosting balls out of the freezer, just a few at a time, and dip them into the chocolate coating, and then sit them on a sheet of wax paper. Because they are so cold, the chocolate will set quickly, so make sure to immediately to add your sprinkles after dipping each ball.
Repeat with remaining frosting balls.
Store in refrigerator.