Preheat the oven to 375°. Line a baking sheet with foil.

On a flat surface, slice the jalapeños lengthwise (wear rubber gloves). With a small spoon, scrape out the seeds and ribs from each jalapeño and discard. Set jalapeño halves aside.

In a bowl, mix together the cream cheese, half the cheddar cheese, the onion and the cilantro. Stir to combine. Season the mixture with the salt, black pepper and cumin. Stir to combine.

With a spoon, fill the peppers with the cream cheese filling. Arrange the peppers on the baking sheet and sprinkle with the remaining half of the cheddar cheese.

Bake for 8 minutes, or until the cheese is bubbly and lightly browned and the peppers are softened. Cool for 5 minutes before serving.