Hassayampa Casserole

1 large onion, chopped
1 tablespoon olive oil
1/2 teaspoon cinnamon
3 teaspoons chili powder
3 teaspoons cumin
1 (8 ounce) can enchilada sauce
1 pound fresh tomatoes, diced
10 ounces frozen corn, thawed
1 cup sliced black olives
3 large green chiles, chopped
1 pound shrimp or imitation crabmeat
12 ounces Monterey jack cheese, shredded
12 corn tortillas

Saut