Tortilla Chips with Grilled Corn and Cheddar

2 ears of corn, husked
Extra-virgin olive oil, for brushing
Coarse salt and freshly ground pepper
1 to 2 jalapeno chiles
1 scallion, thinly sliced
2 tablespoons minced fresh cilantro, plus sprigs for garnish
1 tablespoon fresh lime juice
4 ounces cheddar cheese, grated (1 3/4 cups)
24 tortilla chips, preferably lime-chili flavor

1. Preheat grill to medium-high heat. (If you are using a charcoal grill, coals are ready when you can hold your hand 5 inches above grill for 3 to 4 seconds.)
2. Brush corn with oil, and season with salt and pepper. Grill corn and chiles, turning occasionally, until grill marks appear and both are tender, about 10 minutes. Let cool slightly.
3. Cut kernels off cobs, and transfer to a medium bowl. Peel, stem, and seed jalapenos. Cut into 1/8-inch dice, and add to corn.
4. Add scallion, cilantro, lime juice, and 1 1/4 cups cheese to corn mixture. Toss until well combined.
5. Preheat broiler. Arrange chips in a single layer on a rimmed baking sheet. Top each chip with a tablespoon of corn mixture. Sprinkle remaining 1/2 cup cheese over chips. Broil until cheese is bubbly, about 30 seconds. Garnish with cilantro sprigs, and serve immediately.