After watching this episode of America's Test Kitchen, I had to make this! I used canned tomatillos and poblano chiles (28 oz. can) and it tasted wonderful! So fresh and delicious! I didn't think it was too spicy, even using Pepper Jack cheese. Here are the comments from their original recipe:
"You can substitute three 11-ounce cans of tomatillos, drained and rinsed, for the fresh ones in this recipe. Halve large tomatillos (more than 2 inches in diameter) and place them skin-side up for broiling to ensure even cooking and charring. If you can’t find poblanos, substitute 4 large jalapeño chiles (with seeds and ribs removed). To increase the spiciness of the sauce, reserve some of the chiles’ ribs and seeds and add them to the food processor."