The bold truth: You won’t even miss tortillas. The trick is to use a Y-shaped vegetable peeler to peel wide — thin — strips of zucchini. You don’t just want to start on a whole zucchini; halve it lengthwise, then peel strips. These are your tortillas. Next drain them on paper towels; the more moisture you release, the better off your enchiladas will be.
Preheat oven to 350º. In large skillet over medium heat, heat oil. Add onion and season with salt. Cook until soft, 5 minutes, then add garlic, cumin, and chili powder and stir until combined. Add shredded chicken and 1 cup enchilada sauce and stir until saucy.
On a cutting board, use a Y-shaped vegetable peeler to make thin slices of zucchini. Lay out three, slightly overlapping, and place a spoonful of chicken mixture on top. Roll up and transfer to a baking dish. Repeat with remaining zucchini and chicken mixture.
Spoon remaining ⅓ cup enchilada sauce over zucchini enchiladas and sprinkle with cheddar and Monterey Jack.