Step 1

Preheat oven to 350 degrees F.

Step 2

Cook chicken breasts.  I like to poach them.  Arrange in the bottom of a pot and cover with water.  Add a sprinkle of salt (optional).  Cover pot with lid and bring to a boil.  Reduce heat and simmer for 10 minutes.  Turn heat off and let sit for 15 minutes.  Remove chicken.  Test with a meat thermometer (should read at least 165 degrees F).  Use two forks to shred chicken (debone if you're using bone-in).

Step 3

While chicken is cooking, prepare sauce.  Melt butter in a pot over medium heat.  Add flour and whisk until smooth.  Cook, whisking for about 1 minute.

Step 4

Very slowly start to add broth to flour mixture, a few tablespoons at a time, whisking well between each addition.  Mixture will seize up at first, but will gradually thin out as you add more broth.  Continue until all broth is added.

Step 5

Cook, whisking occasionally, until sauce thickens slightly, probably around 5 minutes.  Remove from heat and add yogurt and green chilis. Set aside to cool slightly.

Step 6

Shred cheese.  Mix 1 cup of cheese with shredded chicken in a bowl.  Divide it between the tortillas, roll them up and place, seam side down, in a lightly oiled pan.

Step 7

Pour sauce over pan of rolled up tortillas.  Sprinkle with remaining cheese.  Bake in preheated oven for 20 minutes, until heated through.  Broil for a minute to brown the cheese, if you want.

Step 8

Enjoy! :)