1. Preheat oven to 350 degrees F (175 degrees C). Grease a 9×13 inch baking dish.

2. In a medium saucepan over medium heat, combine cream of chicken soup, sour cream, and margarine. Stir until smooth and heated through.

3. Stir in onion, chili powder, chicken, and green chile peppers.

4. Fill each tortilla with a generous amount of the chicken mixture, roll up, and place seam side down in the prepared baking dish.

5. Pour remaining sauce over the top and sprinkle with Cheddar cheese.

6. Bake in preheated oven for 30 minutes, or until cheese is bubbly and golden.