Carefully place the large eggs in a single layer in a saucepan. Cover with cold water by about an inch. Bring the water to a rolling boil over high heat.
Once the water boils, immediately turn off the heat, cover the saucepan, and let the eggs sit in the hot water for 10-12 minutes for perfectly firm yolks.
While the eggs are sitting, prepare an ice bath by filling a bowl with ice and water.
After 10-12 minutes, use a slotted spoon to transfer the hot eggs directly into the ice bath. Let them cool completely for at least 5 minutes, or until cool enough to handle.
Gently tap and roll each egg on a counter to crack the shell, then peel them under cool running water. Rinse thoroughly to remove any small shell fragments.
Carefully slice each peeled egg in half lengthwise. Gently scoop out the egg yolks into a medium-sized bowl. Place the egg white halves on a serving platter.
To the bowl with the yolks, add the softened cream cheese, mayonnaise, Dijon mustard, chopped pickled jalapeños, and garlic powder.
Mash the ingredients together with a fork until the mixture is smooth and creamy. Season with salt and pepper to taste, mixing well.
Spoon or pipe the yolk mixture evenly into the hollows of the egg white halves.
Garnish with an extra slice of jalapeño if desired. Serve immediately or refrigerate until ready to serve.