Cube chicken 1" pieces. Set aside. Melt butter in large pan; add garlic powder and chicken cubes. When chicken is no longer pink, place in bowl. Meanwhile, mix 1/2 cup Kraft Cheddar Cheese, sour cream, cream of mushroom soup in large bowl. Mix well. Add chicken.
Place chicken layer on bottom of pan, layer with a tortilla shell. Layer chicken mixture, then again with tortilla shell. Layer once more with chicken mixture. Top with remaining Kraft Cheddar Cheese.