Chicken and Cheese Enchiladas

Name: Chicken and Cheese Enchiladas
Ingredients: 3 cups (12 oz./375 g) masa harina; 1/2 tsp. salt; 1/4 cup (2 fl. oz./60 ml) vegetable oil; 2 cups (16 fl. oz./500 ml) hot water; 1 1/2 lb. (750 g) spinach, stemmed; 1 Tbs. olive oil; 1 yellow onion, diced; 1 garlic clove, minced; Salt and freshly ground pepper; 4 cups (1 1/2 lb./750 g) cooked, shredded chicken; 1 cup (8 fl. oz./250 ml) sour cream; 1 cup (4 oz./125 g) shredded mozzarella cheese; 1 cup (4 oz./125 g) shredded white cheddar cheese; 1 cup (4 oz./125 g) shredded yellow cheddar cheese; 2 Tbs. chopped fresh cilantro, plus more for garnish; 1 can (28 oz./875 g) enchilada sauce; 2 green onions, white and light green portions, thinly sliced