Preheat the oven to 325 degrees F. Spray 9x13 inch pan with nonstick spray.
In a large bowl, whisk together cake mix and pudding mix. Add orange juice, oil, eggs, orange zest and vanilla. Use an electric mixer to beat on low speed until well blended, scraping sides as needed.
Pour batter into the prepared pan. Bake for 35 to 40 minutes, just until cake is set and toothpick inserted in the middle comes out clean. Let cake cool completely.
PREPARE THE CAKE BALLS
After cake is cool, scoop chunks of the cake into a food processor and process into crumbs.
Place cake crumbs in a large bowl. Add ¾ of a tub of frosting and 1 tablespoon orange zest. Stir with a sturdy spoon until ingredients are well combined.
Shape frosting/crumb mixture into 1 inch balls and place them on a waxed paper lined cookie sheet. Place the cookie sheet in the freezer or refrigerator just until the cake balls have had a chance to get a little bit firm.
DIP THE TRUFFLES
Melt about a cup of candy melts in a microwave safe bowl (about 2 minutes on high). Stir until smooth.
Use a small spoon to lower a cake ball into the melted chocolate and swirl it around until completely covered with the chocolate. Scrape the spoon against the side of the bowl and carefully remove the cake ball from the chocolate and set it on waxed paper.
Immediately top with decor and let sit to dry. Continue with remaining cake balls and chocolate. Assembled truffles can be kept at room temperature or in the refrigerator until ready to serve.
Notes
When you bake your cake, you may end up with the top of the cake as a brown layer. If you don't want that brown layer to be mixed into your crumb mixture, just use a sharp knife or a spatula to gently scrape off the brown top layer of the cake.
If you'd like the center of your truffles to be more "orange" than shown in the photos, add a drop or two of orange food coloring to the mix (or red/yellow).
To make a simple candied orange peel: remove as much of the white pith as possible from orange peel using a sharp knife. Cut the peel into thin strips. Heat a Tablespoon of water in a small pan. Add strips of orange peel and a teaspoon of granulated white sugar. Sauté the peel in the sugar-water until water dissolves. Remove from heat and spread orange peel on a paper towel to dry. Use to top the truffles as decor. (And, it gives a little hint as to what flavor is inside!)