
Preheat oven to 350 degrees.
Season chicken breast with taco seasoning. Bake for 25-30 minutes or until cooked through. Remove from oven and shred.
Combine chicken, onion, sour cream and 1 cup of cheese in a bowl.
Fill tortillas with chicken mixture. Roll, and place seam side down in a 13 x 9 baking dish that has a small amount of enchilada sauce coating the bottom.
Pour over the rest of the enchilada sauce. Cover with foil and bake for about 35 minutes, until bubbly and warm.
Uncover, sprinkle with remaining cheese. Return to the oven for 5 minutes, or until cheese is melted.
Allow to cool for 5 minutes before serving (makes them easier to remove from the pan).