Place 6 whole eggs into a pot. Fill pot generously with cold water and add frozen blueberries. Leave an inch of cold water above the top of the eggs. Set heat to high, to bring the water to a boil.
Once the water reaches a full boil, lower the heat to a low simmer and time the eggs for 3 minutes. Continue stirring the eggs around, alternating direction every other minute as before.
Once 3 minutes has lapsed, cover the pot and remove from heat. Let eggs sit in the covered pot for 7 minutes.
While the eggs are sitting in the pot, prepare a large bowl and fill with ice and cold water.
After 7 minutes, remove the cover and carefully transfer eggs to bowl with ice-cold water. Let eggs sit for about 5 minutes in the ice water to cool. Reserve blueberry water in the pot, and let cool to room temperature.
Remove eggs from cold water. Take egg and carefully crack the shell with the back of a spoon or by gently tapping it on a solid surface, turning the egg in different directions to ensure all parts of the egg are cracked. DO NOT REMOVE THE SHELL.
Transfer room temperature blueberry water into a large stain-resistant bowl and discard blueberries. Place cracked eggs into blueberry water cover bowl, and let eggs soak in the refrigerator for at least 8 hours to dye.
Remove the eggs and discard blueberry water. Carefully peel eggs and set aside.
Take a paring knife and cut each hard boiled egg in half, lengthwise.
Remove yolks from each half of egg white and place into a clean mixing bowl. Take a fork and smash the yolks into soft crumbles.
Take avocado, cut in half, and scoop flesh of one avocado half and add to yolks. Add lime juice, finely chopped onions, jalapeños, salt and pepper.
Using a silicone spatula, blend together ingredients until the mixture resembles a fluffy and creamy paste. Season to taste.
Take a star shaped piping tip and attach to a pastry bag. Place finished yolk mixture into the pastry bag and squeeze downward towards the tip.
Pipe yolk mixture into egg whites. Garnish with cut black olive spiders for an extra spooky effect!