Make the sauce: in a saucepan, heat olive oil over medium heat. Add tomato paste, flour, 2 teaspoons cumin, garlic powder, onion powder, and chili powder. Cook 1 minute, whisking. Whisk in broth, bring to a boil. Reduce to simmer, and cook until slightly thickened about 8 minutes. Salt/pepper to taste, and set aside.
Saute the spinach in olive oil over medium heat for 1-2 minutes until slightly wilted.
In a large bowl, combine beans, 2 cups cheese, spinach, corn, green onions, 2 teaspoons cumin, and cilantro.
Preheat oven to 375. Lightly spray a 9x13 inch baking dish, and pour a small amount of the sauce to coat the bottom.
Generously fill tortillas with mixture, roll up tightly with ends tucked in, and place seam side down in dish.
Pour remaining sauce over the enchiladas, coating evenly. Sprinkle 1 cup cheese on top.
Bake about 20 minutes, and garnish with cilantro and/or green onions (optional).