I start by mixing the ground beef with both packets of taco seasoning in a large bowl until it's evenly combined. Then I split it into two portions, using about two-thirds for regular taco filling and one-third for the eyeball meatballs. Keeping the seasoning consistent means every bite tastes the same, whether it's a meatball or crumbled filling.
I roll the smaller portion of meat into 24 small, one-inch balls and line them up on a baking sheet. They go into a 350°F oven for 15 to 20 minutes, until they're fully cooked and just starting to brown. I like pulling them a few minutes early so they stay juicy instead of drying out under the heat.
While the meatballs bake, I brown the larger portion of seasoned beef in a skillet over medium heat, breaking it up as it cooks. Once it's no longer pink, I stir in the salsa and let it simmer for a few minutes so the flavors soak in. This becomes the base layer inside every taco shell.
Once the meatballs are out of the oven, I dip each one halfway into sour cream, then press a slice of black olive on top to make the "pupil." It's a small step, but it's the one that makes guests do a double take when they walk up to the table.
Finally, I set out the taco shells, taco meat, meatballs, cheeses, lettuce, tomatoes, beans, onion, and guacamole in separate bowls across the table. I like grouping the "eyeball" elements near the meatballs so people know exactly how to build the spooky version if they want it. Everyone just walks down the line and fills their own shell.