In a sauce pan over medium high heat, melt the butter then stir in the flour.
Continue stirring to form a roux. The flour mixtures should turn a golden brown.
At this point slowly, 1 cup at a time, add in the chicken stock. Stirring in between each addition to let it thicken up.
After all 3 cups are in it should start to look like gravy. If it is still a little thin, continue cooking until thick and bubbly.
Add in the diced green chiles, salt, and pepper.
Stir to combine then remove from heat and stir in the greek yogurt.
Set aside.
Chop or shred the chicken breast.
In the middle of each tortilla spread out equal amounts of cheese and chicken in each.
Roll them up by folding in 2 sides, then starting at the open side begin rolling. The sides should remain tucked in and hold all of the contents in.
Place each rolled enchilada in a 9x9 baking dish with the seam side down.
If you have any extra filling, add it to the baking dish on top or to the sides of the enchiladas.
Pour over the enchilada sauce.
Pre heat your oven to 350 and bake the enchiladas for 25 minutes until bubbly.
Garnish with cilantro or green onion. Enjoy!