Roast the poblano peppers, then peel, remove veins and seeds, and slice into strips.

In a skillet, sauté the sliced onion, then add the poblano strips.

Roast the tomatoes, remove the charred skin, blend, then cook with the tomato purée. Season to taste.

In a skillet, lightly fry the corn tortillas (preferably day-old) so they are not too crispy but not too soft.

In a baking dish, spread a little tomato sauce, then layer tortillas, some shredded chicken, more sauce, poblano and onion mixture, crema, and cheese. Repeat layers until all ingredients are used. Bake for about 20 minutes, until the cheese is melted and lightly golden.