In 9 x 13 baking dish, place sliced zucchini in a single layer and sprinkle with salt, repeating with remaining zucchini. Set aside for 30 minutes. Salt will pull away moisture from zucchini making less watery chicken and zucchini casserole.
Sprinkle chicken with 1 tsp taco seasoning and using tongs toss to coat. Preheat large skillet on medium heat, swirl oil to coat and add chicken. Cook for 5 minutes or until white edges appear, turn and cook for 5 more minutes or until cooked through. Transfer to a cutting board and shred with 2 forks. Set aside.
In a medium bowl, add tomato sauce, 2 tsp taco seasoning, jalapeno, maple syrup, cumin, garlic powder, salt and pepper; stir to combine and set aside.
Preheat oven to 375 degrees F. Pat dry each zucchini layer with paper towels transferring to another dish (plate). You want to absorb moisture between each zucchini layer as much as possible.
Wipe dry the baking dish, spread a few tablespoons of tomato sauce mixture and sprinkle with quinoa (helps to absorb liquids). Place sliced zucchini overlapping a bit to create a single layer. Top with 1/3 of shredded chicken, then a bit of cheese (reserving a bit more than half for the top) and 1/3 of tomato sauce. Repeat until you run out of ingredients finishing with a layer of zucchini, topped with a bit of tomato sauce, then sprinkled with remaining cheese.
Bake covered with aluminum foil or silicone lid for 30 minutes, then uncover and bake for another 20 minutes. Let stand for 20 minutes before slicing. Cut into 8 slices and serve hot.
Notes
Store: Refrigerate in an airtight glass container for up to 5 days.
Make ahead: Meal prep, assemble and refrigerate tightly covered for up to 24 hours. Meat is cooked, so it is safe. Then bake as per recipe.
Do not freeze:Not ahead, nor the leftovers.
Chicken: You can use any cooked chicken.
Zucchini slices: You can slice zucchini using a mandoline or grater with a slice blade (I highly recommend to wear cut resistant gloves). If you would like a nice weave of zucchini on top, reserve a bit more than for a regular layer.
Low sodium: If using not low sodium tomato sauce, reduce salt.