Meanwhile, in a small blender (I used a Magic Bullet), combine avocados, cilantro, coconut milk, jalapeno, garlic and chipotle powder. Pulse until mixture starts to smooth out.
Carefully drain tomatillos and place in blender with avocado mixture. Pulse a few more times until avocados and tomatillos are well blended.
Pour avocado mixture into skillet with spinach and stir. Pour mixture into a greased 2 quart baking dish and sprinkle with shredded cheese.
Bake at 425F for about 15 minutes or until cheese starts to bubble and brown.