Place the eggs in a saucepan and cover with water. Bring to a boil, then remove from the heat and let the eggs sit, covered, for about 10–12 minutes. Transfer the eggs to ice water and let them cool completely.
Peel the eggs and slice them in half lengthwise. Carefully remove the yolks and place them in a bowl.
Mash the egg yolks with the mayonnaise, mustard, and relish until smooth. Season with salt and pepper, then add a few drops of green food coloring and mix until you reach the desired color.
Spoon or pipe the green filling back into the egg white halves.
Slice the black olive into small rings and place one in the center of each deviled egg to create the pupil.
Add finely chopped chives or green onion around the olive for extra detail.
Use a small amount of red decorating gel or red food coloring to draw thin, irregular lines across the egg whites to create the bloodshot-eye effect.
Refrigerate until ready to serve.
Recipe Notes
For the best presentation, add the olive pupils and bloodshot details shortly before serving.
These spooky deviled eggs make a fun Halloween appetizer for parties, potlucks, classroom celebrations, or family Halloween gatherings.