Preheat the oven to 425 degrees Fahrenheit and line a large, rimmed baking sheet with parchment paper for easy clean-up. Cut off one-third of each pepper lengthwise. Use a small spoon to scoop out the seeds and membranes from each pepper, and discard those pieces.
In a bowl, combine the cream cheese, ¼ cup chopped cilantro and green onion, garlic powder, onion powder and salt. Stir to combine.
Stuff the peppers with the cream cheese mixture. Top each of the peppers with a small mound of cheese lengthwise.
Bake for 10 to 13 minutes, until the cheese is bubbling and starting to turn golden.
Meanwhile, stir the feta, if using, and the remaining 1 tablespoon of cilantro and green onion.
Transfer the jalapeño poppers to a large serving dish and top each pepper with the mixture.
Serve and enjoy!