Preheat oven to 350 degrees, spray a 9" x 13" casserole dish with non-stick spray then set aside.

Heat oil in a large sauté pan over medium heat until it shimmers. Season the chicken breasts lightly with salt and pepper then add them to the skillet. Cook until no pink remains and the breasts are cooked all the way through. Transfer the chicken to a plate and set aside to cool slightly.

Add the flour to oil that remains in the skillet and whisk to combine. Cook the flour in the oil for about 1 minute, then slowly pour in milk, whisking constantly, until no lumps remain. Allow the mixture to come to a bubble, then add ½ cup enchilada sauce and salt. Momentarily remove the skillet from the heat while you shred or chop the chicken.

When the chicken is ready, return the skillet to medium heat and bring the sauce back to a bubble. Add the chicken, stirring well to combine. When the sauce achieves a bubble, reduce heat to medium-low then simmer about 5 minutes until the mixture becomes very thick. Add 1 cup of cheddar cheese then stir to combine. Remove pan from heat and set aside.

Brush the corn tortillas front and back with oil. Heat each tortilla in a nonstick skillet set over medium heat. Cook on both sides just long enough to heat through and completely soften—about 1 minute each. Once all 12 tortillas have been heated, gather all the components so you can begin assembling the enchiladas.

Divide the filling into 12 roughly equal portions and place the filling in the center of the warm tortillas. Roll the tortilla closed and place, seam side down, in the prepared casserole dish. Repeat with remaining filling and tortillas.

Pour the remaining enchilada sauce over the top of the rolled enchiladas and top with remaining shredded cheese.

Bake 15–20 minutes or until hot and bubbly. Remove from the oven and let cool for about 10 minutes before serving. Enjoy!