Place chicken in crockpot and season with salt, pepper, garlic powder, and chili powder. Pour over salsa verde or enchilada sauce; cover and cook on High for 2 hours or Low for 3 ½ hours.
Shred chicken and stir in sour cream. Reserve ¼ of the tortillas and stir in remaining tortilla pieces along with 1 ¼ cups cheese. Top with reserved tortilla triangles and remaining cheese. Cover and cook on High for 1 hour.
Let stand 5 minutes before serving. Serve topped with desired toppings.
