Preheat oven to 350 degrees. Grease a 9x13 cake pan. Cut a square of parchment paper and lay it in the bottom of the pan. Then, grease the parchment paper.
Prepare the box cake mix as directed. My cake called for 3 eggs, 1 cup of water, and ½ cup of oil. I whisked until the lumps were gone.
Bake about 30 minutes or until done. Cool on cooling rack.
Crumble the cake in a medium dish. Add buttercream and mix until everything is incorporated.
Scoop out onto a parchment covered cookie sheet with a cookie scooper or teaspoon.
Chill in the refrigerator for at least an hour.
To Prepare Melting Chocolate
Put the candy melts and shortening in a microwaveable dish and microwave for 30 seconds. Take the chocolate out and stir. Put back into the microwave and go another 30 seconds. Take the chocolate back out and stir. Repeat until there are no lumps left into the chocolate.
Take the chilled cake balls out of the fridge. If you choose to use cake pop sticks, place the stick in the chocolate and then stick it in the cake pop. Do that with all of the cake balls and pop back in the fridge for 10 minutes for the seal to harden.
Take the pops back out, and dip one at a time into the chocolate. I use a foam square to keep the cake pops stuck upright to dry.
You can go ahead and add sprinkles now.
For modeling chocolate decorations
Place white chocolate chips and shortening into a microwaveable bowl. Microwave in 30 second intervals and stir after every 30 seconds. Do this until the chocolate is completely melted.
Add the 1 tablespoon of corn syrup and stir. The chocolate will look like it's seizing up. This is how it's supposed to look. Keep stirring until it forms a ball.
Wrap the ball of chocolate and place on the counter overnight.
When you're ready to use it, use corn starch on the counter top so the chocolate doesn't stick. Roll out the modeling chocolate and use small cutters to cut out shapes.
I used gel paste color to color mine. I kneaded it with the color until it was completely incorporated. I then rolled mine out.
Stick the modeling chocolate cut-outs onto the wet coating chocolate.
Notes
Modeling chocolate adapted from Woodlandbakeryblog.com