Preheat the oven to 350°F (180°C). Season the chicken breasts with taco seasoning and bake for 25-30 minutes, or until fully cooked. Once done, remove from the oven and shred the chicken.

In a bowl, combine the shredded chicken, diced onion, sour cream, and 1 cup of shredded Cheddar cheese.

Spread a thin layer of enchilada sauce on the bottom of a 13x9-inch baking dish. Fill each tortilla with the chicken mixture, roll it up, and place it seam-side down in the dish.

Pour the remaining enchilada sauce over the rolled tortillas, cover the dish with foil, and bake for 35 minutes, or until the enchiladas are hot and bubbly.

After baking, remove the foil and sprinkle the remaining shredded Cheddar cheese on top. Return the dish to the oven for an additional 5 minutes, or until the cheese has melted.

Let the enchiladas cool for 5 minutes before serving.

Enjoy while hot!