Step 1

Preheat the oven to 350 degrees F (175 degrees C). Lightly grease a 9x13-inch baking dish.

Step 2

Heat a skillet over high heat. Add butter, mushrooms, and onion and cook until onions are translucent, 7 to 10 minutes. Add spinach and toss until wilted, about 3 minutes more. Season with salt and pepper. Remove from heat and set aside.

Step 3

Heat a small saucepan over medium heat. Add diced tomatoes, neufchatel cheese, 8 ounces sour cream, and cumin. Stir until thoroughly mixed, about 1 minute, and remove from heat.

Step 4

Place tortillas between 2 paper towels and heat in a microwave oven until warm, 30 seconds to 1 minute.

Step 5

Scoop about 2 tablespoons spinach mixture, 1 tablespoon cream mixture, and 1 to 2 tablespoons shredded Monterey Jack cheese into a tortilla. Roll up and place seam-side down in the prepared baking dish. Repeat with remaining tortillas. Spread any remaining cream mixture on top of enchiladas. Sprinkle any remaining Monterey Jack cheese on top. Cover.

Step 6

Bake in the preheated oven until heated through, about 20 minutes.

Step 7

Garnish individual servings with remaining sour cream and salsa.