1. Line a large baking sheet with parchment. Place popcorn in a large bowl and remove any unpopped kernels.

2. In a medium saucepan over medium heat, combine sugar, corn syrup, butter, and salt; stir until sugar dissolves and mixture begins to bubble.

3. Cook without excessive stirring until the syrup reaches about 270°F (soft-crack stage), 5–7 minutes. If no thermometer, drop a little into cold water—it should form firm threads.

4. Remove from heat; stir in vanilla (if using) and enough red food coloring to achieve a bold crimson hue.

5. Immediately drizzle the hot glaze over the popcorn, tossing quickly with a heatproof spatula to coat evenly.

6. Spread coated popcorn onto the lined sheet in a single layer. Cool 10–15 minutes until dry and crisp.

7. Break apart any large clusters. Fold in optional candy eyeballs, gummy worms, or chocolate chips.

8. Serve in spooky bowls or bag into favors. Store airtight at room temperature for up to 3–4 days.