Directions:
1. Preheat oven to 350 degrees F. Grease a 9×13-inch baking dish or 3-quart casserole.
2. Make the sauce by melting the butter in a heavy skillet over medium-low heat.
3. Add the garlic, cumin and chili powder, and sauté for a minute or two.
4. Raise the heat to medium. Quickly sprinkle in the flour and stir to mix.
5. Pour in a small amount of the chicken broth, stirring constantly to remove lumps.
6. Gradually add the remaining chicken broth and the buttermilk and continue stirring until sauce has thickened, 3 or 4 minutes. Add salt and pepper to taste.
7. Make the filling by warming a heavy skillet over medium heat, then adding the olive oil.
8. Sauté the chopped onion, green pepper, poblano, chiles and tomatoes until onion is transparent, about 4 or 5 minutes.
9. Fold into the mixture the shredded chicken and green onions, combining well. Remove from heat.
10. In a small skillet, heat about half an inch of canola oil.
11. Using tongs, dip the tortillas in the hot oil one at a time, for just a few seconds, so that they are softened.
12. Cover the bottom of the baking dish with 4 of the softened tortillas.
13. Layer the remaining ingredients in the following order:
Half of the chicken/vegetable mixture
Half of the grated cheese
Half of the sauce
The remaining 4 softened tortillas
The remaining chicken/vegetable mixture
The remaining grated cheese
The remaining sauce
14. Bake for 30 minutes at 350 degrees F until casserole is heated through and bubbly.
15. Serve with a tossed salad and your favorite salad dressing.