Preheat the oven to 350°F and lightly grease a rectangular baking dish.
Heat the oil in a large skillet over medium heat then add the onion – season with salt and pepper.
Cook the onion until browned, stirring often, about 5 minutes.
Stir in the garlic, chili powder, and cumin along with the shredded chicken and 1 cup of enchilada sauce.
Simmer for 10 minutes while you prepare the zucchini “tortillas”.
Use a mandolin or vegetable peeler to peel the zucchini lengthwise into thin slices.
Take four slices of zucchini and lay them out on a cutting board, the edges overlapping slightly to form a tortilla shape.
Spoon about 2 tablespoons of the chicken along the length of the tortilla about ½ inch from the edge then carefully roll it up and place it in the baking sheet.
Repeat with the rest of the zucchini and chicken mixture, filling the baking dish with a single layer of roll-ups.
Pour the rest of the enchilada sauce over the rolls-ups and sprinkle with cheese.
Bake for 20 minutes until the cheese is melted and lightly browned then serve hot with sour cream and fresh cilantro.