Preheat and prep the pan: Heat your oven to 375°F (190°C).
Lightly grease a 9x13-inch baking dish and spread a thin layer of enchilada sauce on the bottom.
Sauté the aromatics: In a large skillet, warm the olive oil over medium heat. Add the onion and cook until softened and slightly translucent, about 3–4 minutes.
Cook the mushrooms: Add the sliced mushrooms and a pinch of salt. Cook, stirring occasionally, until they release their moisture and turn golden in spots, 6–8 minutes.
Add spinach and garlic: Stir in the garlic and spinach.
Cook until the spinach wilts, about 1–2 minutes. Season with cumin, chili powder, smoked paprika, salt, and pepper. Remove from heat.
Build the filling: In a large bowl, combine the shredded chicken, sautéed vegetables, sour cream or Greek yogurt, and 1 cup of the shredded cheese.
Mix until evenly combined and creamy. Taste and adjust seasoning.
Warm the tortillas: Wrap tortillas in a damp paper towel and microwave for 30–45 seconds, or warm briefly in a dry skillet. Warm tortillas roll without cracking.
Fill and roll: Spoon a generous 1/4 cup of filling onto each tortilla. Roll snugly and place seam-side down in the baking dish.
Repeat with remaining tortillas.
Sauce and cheese: Pour the remaining enchilada sauce evenly over the rolled tortillas. Sprinkle the remaining 1/2 cup cheese on top.
Bake: Cover loosely with foil and bake for 15 minutes. Remove the foil and bake another 8–10 minutes, until the cheese is melted and the edges are bubbling.
Finish and serve: Let rest for 5 minutes.
Garnish with chopped cilantro and serve with lime wedges. Add avocado, sliced jalapeños, or a dollop of sour cream if you like.