Add the 12 eggs into a large pot and cover with water. Put the lid on the pot and place it on the stove over high heat. Bring the water to a boil. Then turn off the heat and set a timer for 15 minutes.
Remove the lid from the pot and pour out the hot water. Run the eggs under cold water until they're cool enough to handle.
Peel the eggs and cut them in half. Put the yolks into a medium mixing bowl. Place the white onto a deviled egg tray or serving platter. Set aside.
Add the avocado to the yolks and mash until fairly smooth. Add the tomato, onion, cilantro, jalapeno, lime juice, and garlic powder. Stir to combine. Check the seasoning and add salt and pepper to your taste.
Spoon the guacamole filling into the egg whites until filled. (see note) Garnish with a little cilantro and tomato. Cover and refrigerate until ready to serve, up to 8 hours.
Notes
You can add up to a whole jalapeno, depending on how much pepper flavor you want. You can also leave in the seeds if you want your eggs spicier.
I usually have about 1/4 of the guacamole mixture left over. You can either overfill the egg whites or enjoy the remaining filling as a snack. I like to eat it with a spoon, spread it on some toast, or add it to a southwest chicken salad.