Follow these detailed steps to create restaurant-quality spinach enchiladas at home. The process is straightforward and can be broken down into preparing the sauce, making the filling, and assembling the final dish.

Step 1: Prepare the Homemade Green Enchilada Sauce

1. Roast the Vegetables: Preheat your oven’s broiler to high and adjust the oven rack to be about 6 inches from the heat source. Spread the husked tomatillos, chopped white onion, jalapeños, and whole garlic cloves on a foil-lined baking sheet.
2. Broil Until Charred: Place the baking sheet under the broiler. Broil for 5-7 minutes, until the tops of the vegetables are blistered and blackened in spots. Using tongs, carefully flip the vegetables and broil for another 4-5 minutes until the other side is also charred. This charring process is crucial as it develops a deep, smoky flavor that you can’t get otherwise.
3. Blend the Sauce: Carefully transfer the roasted vegetables and any juices from the baking sheet into a high-powered blender. Add the packed cilantro, 1/2 cup of the vegetable broth, salt, and cumin. Blend on high until the sauce is completely smooth. Be cautious when blending hot liquids; start on a low speed and gradually increase, and ensure the lid is vented.
4. Simmer and Thicken: Heat 1 tablespoon of olive oil in a medium saucepan over medium heat. Once shimmering, carefully pour the blended sauce into the pan (it may spatter). Bring the sauce to a gentle simmer and cook for 10-15 minutes, stirring occasionally. This step melds the flavors and thickens the sauce slightly. If it becomes too thick, stir in the remaining 1/2 cup of vegetable broth until you reach your desired consistency. Taste and adjust seasoning with more salt if needed. Set aside.

Step 2: Create the Creamy Spinach and Cheese Filling

1. Cook the Spinach: In a large skillet or pot, heat a splash of olive oil over medium heat. Add the fresh spinach in batches. It will look like an impossible amount, but it wilts down quickly. Stir continuously until all the spinach is wilted, about 5-7 minutes.
2. Drain the Spinach (The Most Important Step!): Transfer the wilted spinach to a colander. Let it cool for a few minutes until it’s safe to handle. Now, for the critical part to prevent soggy enchiladas: you must squeeze out as much water as possible. You can do this by pressing it against the colander with a spoon, or by taking handfuls of the spinach and squeezing it firmly with your hands. You will be amazed at how much liquid comes out. Once thoroughly drained, give the spinach a rough chop.
3. Combine the Filling Ingredients: In a large mixing bowl, combine the chopped, drained spinach, softened cream cheese, 2 cups of shredded Monterey Jack cheese, crumbled Cotija cheese, sliced green onions, cumin, garlic powder, salt, and pepper. Stir everything together until it’s well combined into a thick, creamy, and cohesive filling. For an extra creamy and integrated filling, you can stir in about 1/4 cup of your prepared green enchilada sauce.

Step 3: Assemble and Bake the Enchiladas

1. Preheat and Prepare: Preheat your oven to 375°F (190°C). Pour about 1 cup of the green enchilada sauce into the bottom of a 9×13 inch baking dish and spread it evenly to coat the surface. This prevents the enchiladas from sticking.
2. Warm the Tortillas: To make the corn tortillas pliable and prevent them from cracking, you need to warm them. You can do this in a few ways:
   • Lightly Fry: Briefly fry each tortilla in a hot, lightly oiled skillet for about 15-20 seconds per side.
   • Microwave: Wrap a stack of tortillas in a damp paper towel and microwave for 45-60 seconds until they are soft and steamy.
3. Fill and Roll: Set up an assembly line. Take one warm tortilla and spoon about 1/4 cup of the spinach filling down the center. Roll the tortilla up snugly and place it seam-side down in the prepared baking dish. Repeat with the remaining tortillas and filling, arranging them tightly in a single layer.
4. Sauce and Cheese: Pour the remaining green enchilada sauce evenly over the top of the rolled enchiladas, ensuring all the tortillas are completely covered. Sprinkle the remaining 1.5 cups of shredded Monterey Jack cheese over the top.
5. Bake to Perfection: Place the baking dish in the preheated oven. Bake for 20-25 minutes, or until the sauce is bubbly and the cheese on top is completely melted and beginning to turn golden brown at the edges.
6. Rest and Serve: Remove the enchiladas from the oven and let them rest for at least 5-10 minutes before serving. This allows them to set up, making them easier to serve without falling apart. Garnish generously before bringing them to the table.