layered tortilla casserole

When I read Dana's post featuring this recipe, I knew I would make a version of it. I bought portobello mushrooms and swiss chard but by last night, when I came to make this the chard was severely wilted and did not recuscitate in cold water, so I picked some of ours from the garden (yes!). But my plans for the sauce went awry from the beginning. I was having one of those days when things don't go right, so when I couldn't get the jar of roasted red peppers open, that I was planning to use in the sauce instead of the pasilla peppers Dana called for, I took it as a sign that I wasn't going to use red peppers in my casserole. Instead I made a bechamel sauce in place of the sauce and the cream in the recipe, and added creamed corn. It worked for us, my husband's gerd stomach was happy and we thought it was delicious.

Layered Tortilla Casserole (based on a recipe from Dana Treat)

For Sauce:
3 tbsp butter
3 tbsp flour
420 mL milk
1 can (396 mL) creamed corn
½ tsp. ground cumin
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
1 can 396 mL black beans, drained
8 flour tortillas, halved
6 ounces feta cheese

Make the sauce:
Melt the butter over medium high heat. Add the flour and the milk and whisk until smooth. Heat to a boil, then reduce the heat to a simmer and cook for 5 minutes. Add the cumin and corn and seasoning to taste.
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. Process to a rough paste in a food processor adding water or bean broth to thin the beans, if necessary, to an easily spreadable, but not runny, consistency.  Taste and season with salt.
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, and half the cheese.  Top with the mushroom mixture.  Add a final layer with the remaining tortilla halves, remaining sauce, and cheese.  I added some grated parmesan on on the top of the casserole. Bake, uncovered, until bubbly, about 20 minutes.  Let stand for a few minutes to firm up, then cut into squares.