This dish starts out as classic chili rellenos, with fresh poblano chiles, roasted, peeled and stuffed. However, instead of frying the chilies, they are nestled into a bed of rice, a sauce is poured over; and they are baked.
This is a good make-ahead dish, to assemble the evening before, and then just bake it 25 minutes before you are ready to serve it.
A note about the Mexican Manchego cheese: it's not the same as the expensive Spanish Manchego. Mexican Manchego is an inexpensive cheese available in supermarkets and is a good melting cheese, if it's not available, jack cheese is a good substitute.