Prepare a sour cream sauce that will serve as a topping for the enchilada. Begin by heating 2 tbsp butter and 2 tbsp flour. Do not allow the flour to brown. Add 1 cup of chicken stock and stir, making sure no lumps form. Add 8 ounces of sour cream and mix with a whisk to make a smooth, white sauce. Season with salt and white pepper. Once smooth, simmer the sauce on a very low flame.
For the filling, heat 2 tbsp olive oil, and sauté ½ cup of chopped onions until soft.
Add sliced mushrooms and sauté until soft.
Add fresh spinach that has been thoroughly cleaned. Cover and cook over a high flame.
Once the spinach has cooked down, take the tortilla and place the filling in the middle, topping it with grated cheese. Roll the tortilla up.
Place foil in your baking dish and add just enough oil to coat it. Place the rolled up enchilada on its seam side down. Make as many as you want. Pour sour cream as topping and some grated cheese.
You can add some sliced chicken or white crab meat to the filling if you desire.
Bake in the oven until the cheese has melted down. Take your enchiladas off the baking tray and serve immediately.