Season the chicken with salt and cook using your preferred method until it reaches 165°F (74°C) in the center (try searing, poaching, or roasting). Let it rest briefly, then shred or chop it into bite-sized pieces.

• Rotisserie chicken or other leftover cooked chicken works here too. You need about 1½ pounds (680 g) total.

Set aside while you prepare the vegetables.

Heat the oil in a large skillet over medium-high heat. Add the diced onion, poblanos, and zucchini with a pinch of salt and your chili or taco seasoning.

Sauté until the vegetables have softened and released most of their excess moisture, about 8–10 minutes.

Remove from the heat and set aside.

Add the cream of poblano, cream of mushroom, diced tomatoes and green chilies, and shredded cheese to a bowl.

Stir until evenly combined. Taste and adjust the seasoning if necessary.

Heat the oven to 375°F (190°C).

Spread a thin layer of the creamy sauce across the bottom of a 9-by-13-inch baking dish. Arrange a layer of corn tortillas over the sauce, tearing them as necessary to cover the dish.

Layer over some of the chicken, seasoned vegetables, creamy sauce, and shredded cheese. Repeat with another layer of tortillas and the remaining chicken, vegetables, sauce, and cheese.

Finish with a final layer of cheese.

Transfer the casserole to the oven and bake for about 25–30 minutes, or until bubbling around the edges and hot throughout.

For more browning, broil for another 1–2 minutes until the cheese is browned in spots.

Let the casserole rest for 10–15 minutes before slicing. Crumble the tostada over the top just before serving.

Serve with hot sauce, sour cream, pickled onions, cilantro, or any combination you like.