1. Preheat oven to 350°. In a small bowl, combine sour cream, spinach and 3/4 of the cheese.
2. Into a 9x13 inch pan, pour a small amount of enchilada sauce to coat bottom of pan. Layer 6 tortillas on bottom of pan.
3. Layer half of the spinach-sour cream mixture, half of onion and 1/3 of the olives over the tortillas. Repeat.
4. Pour the remaining enchilada sauce over the final layer of tortillas.
5. Sprinkle with remaining olives.
6. Bake for 20 minutes.
7. Cut into squares and serve.