"1) Poaching the chicken IS worth it -- tender meat, great flavor & the cooking liquid provides the yummy béchamel. Where I live, it's cheaper to buy a whole chicken than 2 breasts, so I poach an entire chicken (adding extra flavorings) by simmering 45min & sitting in liquid for 1 hr. I use all the meat. Poach the day before.
2) I skip the tortillas as others had issues with texture/ salt from the chips. Instead I add a can of rinsed black beans.
4) I cook the onion/ bell pepper /jalapeño together in a large pan. Gently cooking them gets the flavors melding /improves the texture. When I'm done sautéing them, I put them in a bowl to the side and use the same big pan for doing the mushrooms/ béchamel sauce (don't wash).
5) I cut the cheese in half to no ill effect. Healthier casserole, balanced flavors.
To sum, my layers are: black beans, chicken, cooked onions/bell peppers/ jalapenos, ¼ of cheese from recipe, seasoning, mushroom/ béchamel sauce, tomatos/chilis, ¼ of cheese.

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