Rachel's Favorite Enchiladas

• 
  
• 1 tablespoon vegetable oil 
• 1/2 onion, chopped 
• 3 qts. baby spinach 
• 1 cup frozen corn 
• About 1 can (19 oz.) enchilada sauce
• 9 all-corn tortillas, quartered
• 1 cup refried beans 
• About 1 cup cooked rinsed black beans
• 1 cup plus 2 tbsp. shredded Monterey jack cheese 
• 6 tablespoons chopped green onions 

1. Preheat oven to 375°. Heat oil in a large frying pan over medium heat. Add onion and cook until translucent, about 4 minutes. Add spinach and cook, stirring as needed, until almost completely wilted. Add corn and cook until hot. Set aside.
2. Put 6 ovenproof baking dishes* (each about 12-oz. capacity) on a rimmed baking sheet. Working with one dish at a time, spoon in 2 tbsp. enchilada sauce. Top with 2 tortilla quarters, 2 rounded tbsp. each refried beans and black beans, 1 tbsp. cheese, and 2 more tortilla quarters, pushing tortillas down gently as you layer them over cheese and beans. Spoon in 1/3 cup (packed) vegetable mixture, then 2 more tortilla quarters, 3 tbsp. enchilada sauce, and 2 tbsp. cheese. Repeat layering with remaining dishes.
3. Bake enchiladas until bubbling, cheese is melted, and tortillas are starting to brown on edges, about 30 minutes. Sprinkle with green onions.