Crumb your leftover cake finely in a large bowl, then add softened cream cheese and mix until the mixture is dense but pliable, like play-doh.
Use a scoop to portion out small, even-sized balls about the size of a walnut, then roll them gently between your palms to smooth out the shape.
Insert a cake pop stick or toothpick into each ball, then place the balls on a tray and chill in the fridge for 30 minutes until firm and cold.
While they chill, melt your chocolate in a double boiler or microwave, stirring until smooth and shiny.
Dip each chilled cake ball into the melted chocolate, swirling gently to coat evenly, then let the excess drip off.
Place the coated cake balls on a cooling rack, and while the chocolate is still wet, pipe red gel onto the surface to create bloodshot veins or add small drips for gore.
Use a fine-tipped brush or toothpick dipped in food gel to draw irises and pupils in vivid colors, positioning them carefully for a creepy, realistic effect.
Add small red lines radiating from the iris or tiny blood drips with gel to enhance the bloodshot look, layering as needed for depth.
Allow the chocolate to set at room temperature or in the fridge for about 15 minutes until shiny and firm to the touch.
Once set, remove the eyeballs from the rack, and if desired, stick them on a platter or foam block for display. Enjoy their creepy, glossy look and gooey interior.