Preheat the oven to 350ºF. Spray a large baking dish with cooking spray.
Place the jalapeno, garlic, lime zest, peppercorns, salt, and chili powder in the bowl of a food processor. Stream in the olive oil with the motor running, then process for a minute or two until a smooth paste forms.
Place the chicken in the baking dish and rub thoroughly with the chili paste.
Bake for one hour or until the meat reads 170ºF on a meat thermometer. Let cool slightly, then remove the meat from the bones, moistening with the drippings as necessary.
Serve in flour tortillas with monterey jack cheese, lettuce, tomatoes, salsa, sour cream, or any other desired toppings.