My sister and I both made this. She made it after me with my suggested changes/additions. We both thought it was wonderful - here it is with changes. We changed raw chiles to roasted, doubled the flour to two tablespoons and added the garlic and cilantro. Actually, she made the famous cilantro rice from this site and just added a tablespoon or so of the puree to her sauce. I used Mexican Crema. She had sour cream and whipping cream so she mixed the two. Very Yummy!

3 or 4 poblanos, roasted, seeded & chopped
1/2 cup milk
4 T. Butter, divided use
2 T. flour
1 clove or more minced garlic
1 T. minced cilantro.
1 cup Mexican Crema
4 boneless skinless chicken breast halves
1 cup shredded manchego, jack or mozarella (I'm using queso quesadilla)

Puree chiles with milk in blender

Make roux with 2 T. of butter & flour, cook until slightly brown

Stir in chile puree and cook until slightly thickened

Turn down heat and add crema, heat until it GENTLY simmers

Meanwhile, brown chicken in large skillet with 2 t. butter, 4 minutes to a side on medium high heat

Put in buttered baking dish, top with sauce and shredded cheese.

Bake at 350 for 20 - 30 minutes until chicken is done.