Prepare a 9X13 inch baking dish by spraying it with non-stick spray.

Prepare the enchilada sauce: Heat 2 Tablespoons of olive oil in a dutch oven, at medium-high heat. When it is hot, whisk in the flour, chili powder, cumin, salt, pepper, and oregano. Allow this to cook for about 5 minutes, whisking often. Whisk in the tomato paste. Then whisk in the chicken stock, until there are no lumps. Leave the sauce on the heat, simmering (we want it to simmer for at least 15 minutes, more is fine).

Prepare the filling: Place 2 Tablespoons of olive oil into a large skillet and heat it to medium-high heat. Add the diced onion and allow this to cook for 5 minutes. Then add the minced garlic and allow that to cook for another minute. Add the diced chicken and stir to saute this for 5-10 minutes, or until the chicken is cooked through. Stir in the green chilies and cook just until heated through. Spoon a little enchilada sauce into the prepared baking dish (just enough to coat the bottom).

Preheat the oven to 350 degrees.

Prepare the tortilla shells by lightly frying them in the remaining 2 Tablespoons of olive oil. (do them one at a time for about 10 seconds per side, at medium high heat). Then place them on paper towels to absorb excess oil.

Spread a little enchilada sauce on each tortilla and place about ¼ cup of filling down the center of each tortilla. Roll up the tortillas and place them seam side down next to one-another in the baking dish. Spread the remaining enchilada sauce over top. Sprinkle the cheese evenly over the top.

Bake for 15 minutes or until the cheese is bubbly.

Serve hot with sour cream, shredded lettuce, avocado, or a sprinkle of cilantro.