Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper or foil for easy cleanup.

Heat the olive oil in a large skillet over medium-high heat. Add the sliced mushrooms and a pinch of salt. Cook without crowding until they release their juices and begin to brown, about 6–8 minutes.

Add the chopped onion and cook another 3–4 minutes until translucent and sweet.

Reduce heat to medium. Stir in the minced garlic and cook for 30 seconds, just until fragrant.

Add the spinach in batches, stirring until wilted. If it looks soggy, crank the heat for a minute and keep stirring so it evaporates.

Sprinkle in the oregano, smoked paprika, salt, and pepper. Taste and adjust seasonings.

Turn off the heat and fold in the grated Monterey Jack and cheddar. If using cream cheese, add it now and stir until smooth. Fold in the cilantro if you’re using it.

Lay 4 tortillas flat and evenly distribute the filling among them. Top each with a second tortilla, pressing gently.

Brush the top with olive oil or spray with nonstick spray for crispier edges if desired.

Place the assembled quesadillas on the prepared baking sheet. Bake for about 8–10 minutes, flip each quesadilla and bake another 6–8 minutes, until both sides are golden and the cheese is fully melted.

Let the quesadillas rest for 2 minutes, then slice each into 4 wedges. Serve with sour cream, salsa, or a quick avocado-lime crema.