Spread a very thin layer of sauce on the bottom of the casserole dish, so that the tortillas don't stick. Next, lay down 4 tortillas, or as many as you need to cover the bottom and making sure you have enough for 3 layers.
Spread a layer of the sauce over the tortillas.
Spread half of the shredded chicken over the sauce. Then sprinkle scallions over the chicken.
Sprinkle the coleslaw mix of cabbage and carrots over the chicken.
Add shredded cheese. NOTE, you should have 16oz of cheese, which you will need for 3 layers in total, so be sure to portion it out so that you only use ⅓ of the cheese in this first layer.
Next layer another 4 tortillas over the cheese, then sauce, add the rest of the chicken, and another layer of the coleslaw cabbage and carrots. Now comes the zucchini. Lay the slices to create a single layer. Use any extra to fill in any major holes.
Add another layer of cheese (using another ⅓ of the cheese) and scallions over the zucchini.
Add the final layer of tortillas making sure to fill in any holes with broken tortillas.
Spread the final layer of sauce over top.