Layered Pasilla-Tortilla Casserole with Black Beans, Mushrooms, and Chard
Adapted from Mexican Kitchen
Serves 4-6

I made a lot of changes to this recipe, added in some things, swapped out others, changed the size of the baking dish, but this is still a Rick Bayless recipe.  I used canned beans here because I was short on time but ideally, dried would be best.  This recipe has a lot of components but they come together quickly.  You can always make the sauce the day before.  I would imagine, like lasagne, the whole thing can be assembled earlier in the day and just kept in the refrigerator until you want to bake it.  Add another 5-10 minutes to the baking time if you do so.

For Pasilla Sauce:
½ head of garlic, broken apart but not peeled
6 medium (about 2 ounces) dried pasilla chiles, stemmed and seeded
1 tsp. dried oregano
½ tsp. ground cumin
Olive oil
1 cup vegetable broth
Kosher or sea salt

For the mushroom layer:
2 medium portabello mushrooms, black gills scraped out, thinly sliced
2 garlic cloves, minced
½ bunch of chard, leaves stripped off the stalks, roughly chopped

For the casserole:
1 small white onion, diced
2 cups cooked black beans (I used 1 15-ounce can, drained)
8 corn tortillas
½ cup sour cream or crème fraîche thinned with a little cream or milk
6 ounces cotija cheese

Make the sauce:
Roast the unpeeled garlic on an ungreased griddle or heavy skillet over medium heat, turning occasionally, until soft (they will blacken in spots), about 15 minutes; cool and peel.  While the garlic is roasting, toast the chiles on another side of the griddle or skillet.  Do 1 or 2 at a time:  open them first and press down firmly on the hot surface with a spatula; in a few seconds, when they crackle, even send up a wisp of smoke, flip them and press down to toast the other side.  In a small bowl, cover the chiles with hot water and let rehydrate 30 minutes, stirring frequently to ensure even soaking.  In a food processor or blender, combine the chiles, garlic, oregano, cumin, and about 1/3 cup of the soaking liquid.  Blend to a smooth purée, scraping down and stirring frequently.  (If necessary, add a little more broth to get the blades moving.)

With a rubber spatula, working the pasilla paste through a medium-mesh strainer into a bowl.  Heat about a tablespoon of oil in a medium saucepan, then add the paste and a pinch of salt.  Cook, stirring constantly, until dark and very thick, about 4 minutes.  Stir in the broth and simmer, partially covered, for 30 minutes.  Taste and season with salt.  Keep warm over very low heat.

Preheat the oven to 350ºF.

Make the  beans:
Heat about a tablespoon of oil in a medium skillet over medium heat.  Add the onion and a large pinch of salt.  Cook until brown in spots, about 10 minutes, then add the beans.  Using a potato masher or the back of a large spoon, mash to a coarse purée.  Add water or bean broth to thin the beans, if necessary, to an easily spreadable, but not runny, consistency.  Taste and season with salt.  Cover and keep warm.

Make the mushroom filling:
Heat another tablespoon of oil in a large skillet over medium-high heat.  Add the mushrooms and a large pinch of salt and sauté, stirring occasionally, until the mushrooms start to give off their liquid.  Add the garlic and continue to cook, stirring occasionally, until most of the liquid has evaporated.  Add the chard leaves and sauté until the chard is nice and soft and the pan is mostly dry, about 10 minutes.  Taste for salt and season as needed.

Assemble the casserole:
Spread about 1/3 of the sauce in the bottom of an 8×12-inch baking dish.  Put down a layer of tortillas, just barely overlapping.  Top with the beans, another layer of tortilla halves, another 1/3 of the sauce, half the cream, and half the cheese.  Top with the mushroom mixture.  Add a final layer with the remaining tortilla halves, remaining sauce, cream, and cheese.  Bake, uncovered, until bubbly, about 20 minutes.  Let stand for a few minutes to firm up, then cut into squares.