Preheat the oven to 425 degrees . Slice off one-third of the chiles lengthwise. Seed the chiles to make "boats" for the filling. Finely chop enough of the trimmings to measure 3 to 4 tbsp. (I usually use about half of the total amount, reserving any remaining jalapeno for other recipes, such as salsas.)
In a bowl, combine the chopped jalapeno and Fresno chiles, the cream cheese, onion, garlic, cumin and shredded cheeses. Stir until blended and season with salt and pepper. Spoon the filling into the hollowed-out chiles.
Stir the panko and Parm together on a plate and roll the stuffed tops of the poppers in the panko-Parm mixture. Arrange the poppers on a foil-lined baking sheet and coat with a little cooking spray. Roast until the chiles are tender-crisp and the filling is browned and bubbling, 15 to 18 minutes. Let stand 10 minutes and serve.