Trim 1/4" off the tops of the jalapeños, then hollow out the centers with a pepper corer.
In a bowl, mix the cheese, corn and green onion, salt and pepper.
Stuff the cheese mixture into each jalapeño, to within 1/8" of the top.
Set the jalapeños upright in a jalapeño roaster and put the cut tops back on top. Set the roaster on the grill (over indirect heat) and cover for about 25 minutes. Serve immediately.