01 - Preheat oven to 350°F. Mix yellow cake batter as directed on box with specified eggs, oil, and water. Transfer to a 9x13-inch baking pan lined with parchment and bake for 30 to 35 minutes until a toothpick inserted in the center comes out clean. Allow cake to cool completely before proceeding.
02 - Using an electric mixer, blend cream cheese, cheddar cheese, and powdered sugar in a mixing bowl until smooth and creamy.
03 - Crumble the cooled yellow cake into a large bowl. Add the cheese filling mixture and stir thoroughly until it forms a uniform, sticky dough.
04 - Scoop heaping tablespoonfuls and shape into 24 balls. Arrange on a parchment-lined baking sheet and freeze for 20 minutes to firm.
05 - Melt white chocolate or base candy melts according to package instructions. For colored coating, divide and tint portions with food coloring gel as desired.
06 - Dip each chilled cake ball in the melted coating, permitting excess to drip away. Immediately embed broken pretzel fragments as horns or arms, affix candy eyes, and sprinkle decorations before the coating solidifies.
07 - Let decorated cake balls sit at room temperature or refrigerate for 10 minutes until coatings are fully set. Serve or store as desired.