Make the sauce: Warm 2 tablespoons oil in a saucepan over medium heat. Stir in tomato paste and cook 1 minute.
Whisk in chicken broth, chili powder, cumin, smoked paprika, oregano, onion powder, garlic powder, and cinnamon. Simmer 5–7 minutes until slightly thickened. Season with salt, pepper, and a small pinch of sweetener if desired.
Set aside.
Prep the filling: In a skillet, heat 2 tablespoons oil over medium heat. Sauté the diced onion with a pinch of salt until soft and lightly golden, about 5–7 minutes. Add shredded chicken and 1/2 cup of the enchilada sauce.
Stir to coat and warm through. Remove from heat and fold in cilantro.
Prep the “tortillas”: If using low-carb tortillas, set aside. If using zucchini, slice lengthwise into thin ribbons (a mandoline helps).
Lay slices on a towel, sprinkle lightly with salt, and let sit 10 minutes to draw out moisture. Pat dry.
Assemble: Preheat oven to 375°F (190°C). Spread 1/2 cup sauce on the bottom of a 9x13-inch baking dish.
Working one at a time, place a tortilla (or overlap 2–3 zucchini slices to form a “sheet”), add a spoonful of chicken filling and a little Monterey Jack. Roll tightly and place seam-side down in the dish. Repeat with remaining filling.
Sauce and cheese: Pour the remaining enchilada sauce evenly over the rolls.
Top with the cheddar and any remaining Monterey Jack.
Bake: Bake 18–22 minutes, until the cheese is melted and bubbly. For golden spots, broil 1–2 minutes at the end, watching closely.
Finish and serve: Let rest 5 minutes. Top with sour cream, avocado, cilantro, and green onions.
Serve with lime wedges.